Not a problem, grateful for the help.
It's been happening for as long as I can recall (but that doesn't mean that it's always been like this - I just don't recall when it started, but several years ago).
The only thing I can think of, and this is of course pure speculation, is that I masturbate in a non-traditional fashion (I use three fingers at the base of the head of the penis over my remaining foreskin, with the middle finger positioned at the bottom of the head, one on the left side and another on the right side and then move them up and down - not sure if this description is helpful at all).
Other than that, I have no idea.