saf, Though ineligible, the mod, may have pinpointed the the location of your "marks" at the remnants of the fellow's frenum, your explanation of their location is not at all clear. In the interest of accuracy and of your friends health, perhaps you could look at the diagram at the following site and indicate to us more clearly where the problem lies: Go to http://www.cirp.org/ Scroll down and click on "Anatomy of the Penis and Mechanics of Intercourse". Then scroll down to figure 5, The Circumcised Penis.
The red marks may only be the result of a too aggressive masturbation technique (which is one of the more unfortunate consequences of circumcision), but they could also be the first outward symptoms of the mysterious, incurable disease known as lichen sclerosus.
Though women are more often victims of that malady, men are not immune. In circumcised men, it often appears at or near the scars which relate to circumcision, and the first signs may be a whitish cast on the skin, and sudden sharp, stinging pain, often at the moment of ejaculation. Eventually a small, reddish, blood-like smear may appear, and at times, blood may actually break the surface. The only way lichen sclerosus can be properly identified is with a biopsy, and the only way a biopsy can be arranged is through a doctor.
Regardless of the difficulty or embarrassment your "friend" should see a dermatologist, not a GP, and not an urologist, as they aren't trained to identify skin disease. The penis is too important to have something so potentially serious left unexamined and untreated.