It's one of those times that would make our high school physics teachers proud. Drivers are catching on to the fact that they're paying more than they should for gasoline because of something called "thermal fuel expansion." Never heard of it? Chances are you've paid for it. Here's how it works. If you want to know more, write to us in the comments section and follow us on Twitter: twitter.com/fastdraw We'll be following this issue, which is bubbling up during the recession.