In thermals, not that I've seen - though there are of course far more raptors around than I've flown with.
However, if you fly too close to a buzzard's nest site at the wrong time of year, you'll discover that not only are they quite aggressive, but that they use some *appalling* language... after one occasion being sworn at by buzzards, I've made sure I keep further from their homes. I don't know where they learn that sort of language, though - probably hang glider pilots.
There's not usually any problem flying with them but I suspect that birds judge distance and speed of approach by parallax and see a five-times-bigger-than-them paraglider as five times further away, and there are occasional collisions, as here:
(not safe for work due to swearing in Russian). The bits of string that attach the pilot to the glider make us uniquely vulnerable to collision with birds, if they get tangled.