It did still require joining imgur.
I don't think it's anything to worry about. Interesting things can happen with melanin pigmentation between the inside of the foreskin and the outside, because these are different sorts of skin, joined together. Often there is a difference in colour. You'll notice in your case that the skin on the inside of the foreskin is thinner, and therefore looks redder. Guys with more pigmentation in their skin may show a marked difference in brownness for the two different sorts of skin.
At the junction of the two sorts of skin the skin is thicker, and can look darker from a very small amount of pigmentation. Guys who are circumcised (which means a new junction has been made) usually have a noticeable dark ring there. Your natural dark ring is not as dark.
So I think it's quite natural, and nothing to worry about at all. There is so much variation between penises (far more than between, say, fingers) that 'normal' covers quite a range. But I can't imagine anyone thinking yours looks at all not normal.