Cavemen: Was cave art considered graffiti at the time?

This is a tricky one to pin down.  Large works of art, such as the Lascaux cave art, were most certainly not made on a whim, and were likely associated with ritual and spirituality, owing to the sacred nature of caves in Paleolithic Europe.  It's important to keep in mine that to the paleolithic peoples, caves were sacred sites, they were significant features on the landscape, and therefore not something you'd abuse.   Given the examples we have found in cave art, it seems even the act of making making an image was seen as a sacred one.  Our current understanding of graffiti is one of counter-culture.  In a modern context, it is used to make political or social statements, and by placing them on buildings or structures, it is an attack on establishment.  It's a product of our current civilisation, which Paleolithic peoples would not have yet experienced.  So I would tend to say, no, it was not seen as graffiti.