Contractor Dispute - Am I wrong?

[Cheryl Lane]

I recently had a dispute with a contractor, who took some instructions from my real estate agent when we were prepping the house to be put back up on the market. I never told him to do the things he did, but my agent did - and I didn't say no. They were things that are a bit on the "perfectionist" side and I didn't think is necessary personally. My agent basically asked him to replace a few cover plates and remove a dead rat as well as a few wrapping blankets that were laying down the floor. I already paid almost 10k for his work on other projects, which I discussed prices and agreed to before. He actually came in as a connection from my agent and my agent asked him to "do me a favor". I made the mistake of not asking if he will charge for any of these minor tasks. 

He surprised me with a 500 buck bill and I was not happy about that at all. What would you have done in this situation? Was he being reasonable to do this without asking me if I'm okay with the price and then hit me with a surprise bill?