Aqua, I don't feel you should be criticized for this experience.
A couple of years ago, the same thing happened to me. I've had permission to eyeball arrowheads at a plowed field, just outside the city for 10 years.
The owner, a kind old man was happy to have me there saving history and was one of those rare gems of a person that is hard to find these days.
The field was in the middle of nowhere with no houses nearby.
Anyway, I was doing my thing and a truck pulls up with a middle aged guy spouting off obscenities at me. I walk up and had to tell him to lay off with the f-bombs as he had no right to talk to me like that.
I told him that I had permission and his reply was...."I stuck my dad in a old folks home and now I've taken over this property. Get the

out of here!" I walked away pissed and noticed on the way out a "For Sale" sign.
That greedy fat **** had dollar signs in his eyes, now that he got rid of his nice old father. To this day, I still feel like beating his face to a pulp. That place had provided me with some the best prehistoric artifacts in my whole collection.
I grew up in a small town that's now full of snobby yuppies. These city folk move out to the country and bring their crappy mentality with them.
I could write a book on my experiences with these idiots over the last decade or so.
Yes, things have changed!
Unfortunately, we have to move on to the next spot.
Best of luck.
Dave.