Resume question- is this a big deal?

As resume fibs go, this one is fairly minor. I routinely see resumes where people invent "consulting" or "freelancing" gigs to cover periods of unemployment that fall apart completely at the interview. However, I don't see the value in the fib, since a five month gap or a three month gap don't seem all that much different to me. I can't imagine that it would significant affect your previous supervisor's reactions to you -- either you are reading him wrong or there is a different reason for his reaction.

Nthing - anyone who is even noticing this fuzz in the chronology has other bees in his or her bonnet. As a hiring manager and for my own resume, I consider fabrications to be highly material witnesses to the character and qualifications of the applicant, omissions or vague situations not so much. I could wish that more people would omit their waitressing jobs they had in college that make their resume run 3 pages when they're now 40 and a CPA, because it means nothing (unless they're now applying to be a waitress). In a similar way, and as has been said above, you've got a gap in employment, wherein you started or tried to start a business, and it's fair to say either that you were at least working on it or brainstorming at some level for 5 or that for 3 months the business was actually up and running. Either statement is the truth, and his or her reaction is not your problem.

All the gaps in my and my husband's resumes are credited to freelancing. Unless there is some sort of regulatory or licensing requirement that you carefully log your work hours, which you've said is not the case, I suspect that your old supervisor has problems of his own that have nothing to do with you.

Three months or five months - the gap is not really a big deal either way. The key is to be honest and confident in interviews when you tell them what you were doing in that gap. I had one person in an interview tell me that she took a year off to "work on a self-directed math course." Don't do that.

I don't think anyone would care. I would have never even given it a second thought but I noticed that next time I talked to the old supervisor that he seemed annoyed with me...and the other time I talked to him since then. Usually he is very warm but seems to have no interest in talking to me. This is the only thing I came up with for why. The perceived coldness in demeanor could be the result of a lot of things - stress, mild illness, a personality quirk, that sort of thing. Professors also tend to get new students - and new responsibilities - every year, so perhaps it's a subtle hint that it's time for you to leave the nest.

This is not a big deal. You were out of work for 5 months and in the interim were researching and estabilishing your business. So an old supervisor was annoyed with you? It could have been anything. Perhaps he didn't have time to chit chat. Perhaps he assumed that once you and he no longer worked together, that he didn't ever have to talk with you again. Maybe he was constipated. You have no way of knowing.

I can't imagine how anyone else would be keeping such a close eyes on the chronology of your life/business that a two month difference would even be noticed. It is pretty normal for business to have a soft opening before a larger public announcement that the business really is up and running. The supervisor may have been annoyed that his marriage was ending, his visa bill was too high that month or something in his job changed (or he may not see the point of investing time and energy in a relationship that he is no longer being paid for). That you would be so concerned about your supervisor but unwilling to specifically address it with him as an adult indicates you might want to work out some of your anxieties with a therapist.

I'm in the "does not matter" camp. Businessss take time to set up anyway, and a reasonable argument can be made that you've been working at it for five months, not three. In other words if your business were incorporated on jan 1 2013 it's not unreasonable to assert that you were working on it in nov 2012...

Why would you even lists months on your resume? The year is fine.