Penile Vein on the top ?

HI guys , yesterday I was with my girlfriend and she was doing a handjob when I felt strange(again) , my penis was like numb for a moment.And today I examined it closely - I have very obvious vein on the top of the shaft,it starts from the left side and finishes right before the head in the middle.I’ve had it from very,very long time.It has never bothered me.So I made the exact same handjob that she does and discovered that If I grab the penis too tight in the beggining of the shaft this vein enlargers(due to stopping the blood passing through it).And causes this numb feeling after 1-2 minutes.I watched closely now some amount of porn to see how are the other guys going with this vein s**t, the most of them do not have such vein on the top.So I’m asking if any of you experianced such a thing , or might have idea what could it be - please give me a clue.

I forgot to mention that this vein enlarged itself(about 30%) when I started PE.

You can see from the following illustration that the main veins, arteries and nerves run along the top or dorsal side of the penis. It’s the same for everyone, although the dorsal vein can be more visible on some guys like you. Applying pressure to the point of going numb is not a good thing, so you should avoid doing that. Here is the illustration: penis%20anatomy.jpg