i dont think so because what absorves the microwaves and turns them to heat are the water molecules. water boils at 100 C (212F), therefore in theory is impossible reach higher temperatures than it. even if it were possible, the THC boils at somewhat like 200 C, so there is no need to worry about it.
if you want be sure, microwave just a very small amount of weed... i assure you the weed will just become hot and dry, but no harm will be done to it.