Yaaaay!! Glad he's out and okay......
That actually isn't an odd thing. That happens all the time where they remove any of the remaining baby teeth... especially if they aren't loosening up.
I actually had to take my Riley back 2 months after they have neutered him to have his 2 upper canines pulled. Most vets do it during the neutering. I took Riley at exactly 6-months... my Vet was hoping they would have fallen out right after, but they did not....so he had to go under, again to have them removed.