Have you gone shopping for inkjet photo paper in a while? I've noticed (actually several months ago) that it's just about impossible to find 8x10" paper anymore. Matte, glossy - doesn't matter. Canon, Epson, HP and others just stopped making it. Everything is 8.5x11" ("Letter") sized. Great for putting in a loose leaf notebook, but what the heck? My picture frames are made for 8x10" prints. And I liked not having to trim every print!.
The only way to get it now seems to be by ordering it online at a paper supplier, but even there the inventory is very limited.
Go figure, you can buy crate loads of 4x6" and 5x7" - even 11x14". I guess I was the only one left printing 8x10" and didn't get the memo...