Yeah, stick to your instincts. My daughter 13 and son 11 won't be dating one on one till they are at least 16. I am not sure what some parents are thinking, maybe they don't know either.
But keep in mind if a kid wants to fool around with another, they don't have to be on a one on one date to do that. Just tell the truth on why you have the rules and they might moan and groan, tell you that you are old fashioned or too srict. But they will secretly thank you for it because they can use you as a reason not to get involved in things they aren't ready for and really don't want to do, like sex, drugs, and other stuff. You are doing a good job!