If you're circumcised, the head of the penis is normally wrinkled. It looks like it has crevasses or cracks in it. Its from the head being exposed to the air all the time, and it becomes keratinized which desensitizes it, and forms those wrinkles/cracks.
If you're uncut and getting these, it usually means your foreskin is loose and air is getting under the foreskin and drying the head out. It's no big deal though.