The skin colour under the head of the penis doesnt match the whole thing. the small area right under the glans is white. not itchy or painful, just different colour. should i be worried?

See below : If the only finding is just an area on the penis of different color or skin pigmentation as you described and which has been present for some time without any noticeable change, then not an uncommon occurrence and highly unlikely that it is of any clinical significance. Otherwise, if a concern to you, one can always see a urologist or dermatologist for confirmation.