That's just natural recession. I see hundreds of heads a week. Lots of guys start to stress because their hairlines aren't the same as when they were in their teens. We all go through a bit of a recession when we get into our 20s. Just monitor it and if your hairline starts to really thin out and recede, then you might need to do something about it if it really bothers you. If it stays the same, you will be just fine!