I would get it looked at , for peace of mind , take care ,
It's on the actual head.
I've only found one other post online similar to it.
It's still there but doesn't hurt or anything.
I thought it may be from rough handling but I'm not sure.
It starts in the center of where the foreskin retracts and goes horizontally , you can see blueish coloring when you shine a flash light on it, under normal light it looks the same color as the rest of the area.
Hi Chris is the vein on the Foreskin ? i can't imagine a vein on the Gland itself ,
But if you have a Vein on the penis head i would get it seen to ASAP
it has baffled me , could you explain more if you can ,
Please let us know the outcome , Good luck