Skin concern on my toddler's hand

My son has very fair skin like me. A couple of weeks ago, we noticed a small pea-sized spot on the back of his hand that is paler than the skin around it. When you look at it closely, it almost looks like a pale scar but I am 100% sure that he's never had an injury of any kind in that spot. He's also never had a sunburn.

Maybe just a funny pigmentation thing that's only showing up now because he's been out in the sun more in the summer? Should I be worried about anything worse than that? He has a check-up scheduled for the end of July so I'll definitely ask her about it then but should I be checking into it in advance of that?

Thanks in advance.