You shouldn’t feel offended, but I get it.
When I first started hiring I had no self esteem. I didn’t see my own worth or value, and it led to a lot of hurt feelings and jealousy with providers. It took a couple of years to work out, so I get why seeing that could bring up some feelings for you. As others have said, you have no claim to his time outside of what you paid for and if he can make a lucrative weekend out of his trip, let the man hustle!
I wouldn’t “mention” that you saw him post his ad in your city. That’s a bad look.