I see that you are from Colorado but OCing in South Dakota. I am glad to see that you feel comfortable doing OC here in my state. Just last week I was in Colorado practicing OC.
Chances are that your encounter was with someone from the left coast (California). My anti gun encounters as well as liberal encounters here have mostly been with former Californiaians who have moved here or are visiting.
I hope more of us honest, law abiding folks continue to open carry so more people get the message that open carry is performed by those who do not want trouble but are ready if it comes along. And, the mere fact that you are prepared with a firearm is going to greatly reduce the possibility that trouble will show itself in your presence.
Hope you had a great family vacation. I would be glad to have you around if I needed help out of a situtation.