He looks like he's going grey to me. We owned a palomino filly many years ago that as a weanling, looked like a true golden palomino but as she got older (started around a year old) you could see grey hairs coming through her coat. By the time she was two, you could definitely tell she was going grey. Does your boy have one grey parent?
He's gorgeous either way!! Although a lot of people shy away from greys, I personally love them! If he does go grey, he will be a stunning rose grey since he's a palomino and as he gets older, he will turn lighter in colour, almost white (as all greys do).