Dexter entered my life in November 2012, and ever since I first got him, he has had a little dent near what I would call his eyebrow. It concerned me back then, so I took him to an exotics vet and they told me that with some sheds it'd be fine, and that is was nothing to worry about. Every single shed he has had, the dent has changed. It's gotten a little bigger, to smaller, to hardly noticeable at all, and then back to how it looked it 2012... but this recent shed he had this week has me concerned. It has seemed to turn into a crater-like dent? There is no discharge, no strange behavior, and it doesn't appear to be painful, but I'm just confused with why it has suddenly come back, and it so much larger than it's ever been? Here are some pictures (see from the second angle how it kinda looks like a dent?):


Just wondering if this is just another weird shed, or something else? Has anything else experienced anything like this? I'm just feeling concerned because it's near his eye, and I don't want anything to happen to his gorgeous eyes! Any help or knowledge on this would be much appreciated.
Thanks in advance, everyone, and I'm happy to have finally joined this forum!