I'm sorry that happened to you. =[
When we took Fozzie in to get neutered (at 6 mos), he was still losing baby teeth, and his canines hadn't come out yet. My Vet examined him before-hand and told me they might remove the teeth if they're loose enough. They also gave me the option of signing a release that stated to do NO extra procedures, to do extra procedures only after calling & telling us about it, or to do extra procedures if needed. I asked that they only do any extra stuff if they called first. They called me, and explained that 3 large baby teeth were loose, and it'd be safer/cleaner to remove them while he's under. I gave them permission and they did end up removing the loose canines, and stitching them up, which was definitely a good thing! I think it costs about $100 extra to remove/stitch/medicate the teeth, but I'd rather be safe than sorry.
I would definitely be disappointed in my Vet if they hadn't even attempted to call me first. It takes, what, 5 minutes max to make a phone call? I'm sure you would have given them the ok to extract the molar anyway, but it's the principle of it.