no I didn't paint the inside of mine. I really don't see a need to, if you're getting enough moisture inside the coop that could promote warpage or rot, you need to find and fix the leaks.....Did you paint the inside of yours ? I really want to move the chicks in painting would put me back by a week between dry time and labor but if it really helps I will do it .
it can help prevent pests though and make it easier to wipe down/keep clean