I got an 8BA '49 block, and one of the valve seats has popped up and is smushed between the valve and the block.
I guess I need to get the thing sent in to a shop or something to get that fixed, but do I need to worry about the other valve seats? Would that have been just a freak, or would it have been from poor work on the seating?
You don't need to worry about the other 15. The tolerance must have been off by just a bit allowing that one to jump out. It happens sometimes. Just have the shop doing your machine work install a new one.