Little smudge on the back of my iPhone

Should I be worried? It doesn't interfere with the pics. But I can't seem to take it off. It's a little smudge. I might be overreacting but I take care of my stuff. Should I just sell it and get a new one?

If it really bother you that much, and getting a new one make you feel at ease, then yes, just sell it and get another one. Why not? Make the most of it and enjoy it.

I'm afraid you may not get full price for your phone since it's used. Yet if it upsets you that much, go for it.