TC - Thanks, I had read through that. My rush was due to the fact that I was making a long-ish trip yesterday and didn't want to risk getting stuck 125 miles from home.
So... I went anyway and had the GASCAP thing blinking at me almost the whole way. From time to time it would let out another chime. Then when I was over 100 miles down the road it started chiming like crazy. The daggone thing sounded like a pinball machine. Bing! Bing-bing!! Bingety-bing-bing-bing!!! I was thinking to myself, "Well, this'll be fun having to pull over, get a tow and a rental, then drive back down to pick it up once it is fixed. And I'll be at the mercy of whoever it gets towed to, since they'll know I'm from out of town and won't be as likely to quibble about things..."
And then it stopped bing-bing at me. And the notice went away and never came back. And stayed that way until I got to where I was going. Never came back the entire trip back, either. I'm going to stick the new gas cap on when it gets here and wait and see what happens next.
Thanks, everyone!