The sudden appearance of leaks is certainly suggestive of a connection to the work. I'm just not clear how refinishing could cause such leaks . . . but then I didn't watch him at work.

I gotta say -- cause I've experienced such things a couple of times -- it could be a terrible coincidence, that has nothing to do with the contractor. Coincidence is not proof of causation, but darn it's hard to prove that to a suspicious customer who had no problems before.

What can make it hard is if (a) it's not his fault, but (b) he has no idea what IS causing the problem. Leaks can be really hard to track down.

Best wishes and good luck . . . to both you AND your contractor!