Did you always have this hard vein or is it something that has occurred through your exercises cause it sounds like you might have a throm. vein, It can occur for multiple reasons: under preparation, over exercising, too much pressure. It also helps to do a proper and thorough(SP??) warm-up/cool-down after wards to get the blood flowing back through the pipes at a normal rate.
I get them once in a while. If this is what you have just take some time off, usually there is a slight pain with them sometimes not but just for precautionary actions take a little time off to see if it goes away.
But that is what it sounds like to me, If you were born that way then congratulations man you have the few naturally ribbed penis' that i have heard about that havn't been created through surgery, or a side effect of pe.
