A.H.
Cafe-au-lait spots are a symptom for a constellation of genetic conditions. For the most part, they're harmless. I have a few, as does my daughter in almost the exact same places - and we both have Ectodermal Dysplasia.
It's just one of those odd things. I wouldn't worry until the doctors find something. It' doesn't actually mean there IS something wrong. Don't worry and try not to read too much into it. The spots are really a broad symptom - it would drive Dr. House nuts!
Don't worry about it. You'll just make yourself sick with worry.