My nephew had this, although I forget at what age they noticed it (around 1 though). It didn't end up being an issue, but I would mention it to your pedi at your appt.
Hmmm...yeah I'd probably want a blood test just to make sure there wasn't something off hormonally. I did worry about my DD1 because she started getting body odor early in my opinion at 6. She's almost 11 now & just starting real puberty. So it could end up being a non-issue. I'm always a bit concerned because my Mom got her period at 9 so I know it can happen early in my family.