Ha, I used to work in a comic book store. We got trivia nerds "upstaging" us all the time, and no, it didn't bother me one bit. I doubt you caused that cast member to go home that day feeling "down in the dumps". I doubt she even remembered you by the time she was on the road home. You were just a very small part of a very long, busy day.
Personally, even if I do happen to know more than the cast member, I don't start dumping info on them. Instead, I make sure they know just how much I appreciate the special attention and the effort they're going to for me. Because I remember exactly how tedious some trivia nerds could be (though I'm not saying you were quite as obnoxious as all that, since you say you were courteous), I try to be polite, and receptive to whatever they want to tell me.
Just because I know something, that doesn't mean I have to share it with everyone.
A couple trips ago, we booked the Christmas Sleigh Ride around Fort Wilderness. The driver was lovely, and very keen to tell us all sorts of "secrets", all of which I already knew and some of which I knew were inaccurate. So what? I let him talk and enjoyed the ride. In the grand scheme of things, it just didn't matter.