as most vets are (bad with reptiles)
It's mostly likely an eye cap! eye caps shouldn't be brought to a vet. There's lots of ways to get them off, but wait until the next shed and give him LOTS of extra humidity and it should come off just fine.
There is some whites on the very edge of most of my ball pythons, some don't have it, but i think it depends on the snake. You probably just noticed it now because you are being over cautious (which is good!) but it doesn't sound like you should worry.
Eye caps look like wrinkled plastic over the eye, or sometimes look like a crease. My big girl had a REALLY bad eye cap, see here:
click here for EYE CAP PIC
I know THAT looks bad, but it came off perfect in her next shed.
Like mentioned, it would be easier if you had a picture of it, so we could confirm and tell you for sure.
It bothers me that most people would send you to a vet that would do more harm than good (and cost you a couple hundred dollars) just for a friggin' eye cap.
Jessy