Bird crap etching starts on contact and stops when the crap is dry. If the surface is hot it just compound the issue as the paint will expand and contract around the crap. Hopefully the etching is not too deep and it will polish out. My Flex Random Orbital gets out Bird Shit marks pretty easy. Always remove Bird Crap as soon as it is discovered.
Current - '11 e92 M3 SG/FR ZCP|ZCV|ZP2|2MK|494|415|6NR|752