LOL my trainer did the same double take at the gym. She used her machine and figured it must be wrong, I couldn't be that low body fat. Then her calipers pretty much said the same thing.

I guess sometimes it's about proportion. I don't look like an athlete. My heart rate is normally 80 (non-exercising) but now it's about 51. I know I'm relatively fit. But I certainly don't fit the "stereotype" of what an athletic body looks like. I don't look overweight, I just have hips!