Question: I'm building a strip canoe and have glassed the out side with one sheet of 6oz. After sanding halfway through the inside I have noticed 1 or 2 spots on the outside that are starting to show signs of the glass creasing inward slightly about 1 foot lengths.

What the heck is going on? never had this happen before.

If your shop is getting dryer (is it snowy winter where you are located?) the wood could be 'shrinking' on the inside.
Adding moisture to the inside surface will confirm or eliminate this hypothesis pretty quickly.
If the wood was a bit 'green' when you glassed the outside the same thing could happen.