Baking sucks, and as Rosie said, it depends on how long it was baked for, the longer you bake it for the longer it starts to affect the metal itself, but generally once its been re-anno'd it should be okay (ish) as the old anno is stripped off and then a tiny layer of metal is removed too, but then a new layer of anno is applied, so in no, the new anno wont scratch easier, but the metal itself may be weaker as a whole