Hair thinning only on temples

[luka]

Hello! (First post on here) Recently I've been worried about something. I am 20 and these days it seems like I'm noticing that the hairs on my temples are thinner than last year, and they are thinner than the rest of my hair on the side. However, I must say that my hair on top is perfectly fine, (like you will see in one of the picture) but I'm wondering if thinning on the temples could be a sign that I will start balding and have a receding hairline in the near future... I've always had a quite large forehead, but it's only recently that I've been noticing how thin the hair on my temples are. Should I be worried? What do you think? I put some pictures of my hair.

Thank you!