Based on your description, a foreskin that automatically rolls back and leaves the glans exposed is highly likely to be a normal anatomical variation, commonly known as a natural retraction or a short prepuce (foreskin). For many adult men, the length and elasticity of the foreskin are such that it rests comfortably behind the head of the penis, which is perfectly healthy as long as it does not cause pain or swelling. If this has been the case for many years and causes no pain, discomfort during erections, or restriction, no treatment is required.

Normal only no need to worry during erection if it is painful means need to examine