Huntnteen, I most def. wouldn't wait to see if they come back. Chnaces are if they feel can get away with it there, they will be back at some point. maybe not this yr, but how about next yr.! I would def. talk to the landowner, and inform him of the problem.
I once had landowner permission to turkey & deer hunt. 1 turkey season I ran into a new hunter that told me he had permission from owner. Next day he had a guy with him, following day he had a different guy with him. I learned he was guiding hunters on that land. I spoke to the owner, and asked him if he was aware of this. He said no, and was very upset this guy was making $ off his land. The owner stopped the guy, and he wasn't allowed back.
Think of it this way, if it was your land wouldn't you want to know what was going on??