I know I developed a lot of moles in my teenage years, so it might just be growing up and skin changing. I would get a trustworthy Derm to track it. I grew up in FL, and am super super fair skinned, and have had so many severe sunburns (2nd degree burns when I was 6) that I went to a derm in highschool who told me I definitely needed to be kept an eye on for the rest of my life. Now that I'm on Remicade, I'll have to start going pretty regularly.
By trustworthy I mean not knife-happy. I've been to some that want to cut out and biopsy pretty much all moles, which sounds good in theory but often isn't necessary unless it is a really really malicious looking mole. A good one will be receptive to wanting to wait a bit or receptive to some back-and-forth before deciding what to do, some derms even take pictures of questionable moles to refer to at a later date to see if they've changed. Obviously some will eventually need to be biopsied but I have awful scars on my back from having some done by a doctor who I think ordered them on everyone that came in (he later lost his license). Wish I had known to question him at that age, but I didn't.
Good luck!