freckle or mole?

I noticed a brown spot on Evan's belly a few weeks ago and I got all excited thinking it was his first mole. But then when I touched it, it came off on my finger...it was just dirt. Dirty boy. But then a few weeks later, maybe around 9 weeks old, I noticed a lighter color brown spot on Evan's left knee. And this one didn't rub off! It looks like a freckle, like a tiny little baby mole, and 2 weeks later it's still there. It's so cute!