red eared slider shell

Question
My res is about 6 or 7 years old, and the size of a dessert plate.
I have had him since he was a baby and so far no health trouble, so
for the most part I think i am doing ok with habitat, feeding, etc.
But THIS has never happened before, I am not convinced it is normal,
and I need some help. I will of course take him to the vet if
required, but he is a pretty high stress little guy and I dont want
to put him through that if not required.
So- about 2 weeks ago i noticed one whole scute by his back leg
looked a lot different than the other. It was like someone had
pulled a layer of plastic off it to reveal brighter shell
underneath. It looks and feels healthy and hard. Just like he shed
the whole top layer of the scute, which i was told does NOT happen
in healthy turtles, just bit by bit like human skin.
And this morning, on the exact opposite scute by his other hind leg,
again another piece of shell looks like that.  The first area still looks the same, and there was no visible debris in the tank from the shell.  It was definetly not like that previously, and it looks like it came off in one piece.

I got him a new turtle light, checked the temperature of his water,
etc, all seems ok. He was pretty jumpy this morning, but i did take
him out to have another good look at him, and gave his shell a wipe
and a thin coat of vaseline (which i have never done before but had heard it recommended). He was antsy and did a bit more mouth
breathing than normal. Everything else seemed fine.

Is this normal or is this pathological? The only thing i can think
of that has changed is his stress level. Any input appreciated.
Thanks.

Answer
Turtles shed SKIN in little bits, but they shed SCUTES in whole pieces. A normal scute shed is paper-thin, translucent, and the tissue underneath looks healthy and clean.

Scute shedding is not absolutely normal- it usually either reflects fast growth or stress (or a growth period after an illness or poor cares).

The question is are the cares solid, or is the turtle stressed? You can review the cares at a good site like http://www.redearslider.com