I'd go back and see about the fork. Point out the rest, but they wouldn't bother me. It's going to be hard to prove you didn't do it, and I believe you. Sadly many bike shops basically don't believe the customer because they have many people try to pull the wool over their heads. If you get no result, just never go back to them. Not all shops will swallow their pride and admit it was them / may have been them.
I once had a similar problem with a carbon wheel. The bike went in to have a headset put in. It wasn't until two weeks later I noticed a gash in my carbon wheel which had been filled with what looked like superglue. A pretty crappy attempt too. Again, how could I hope to prove I didn't do it?