I KNEW it!

[aroraborealis]

While my cat was using the litterbox, I noticed it was a bit low on litter, so as she was burying her product, I sprinkled some fresh litter on top of where she was scratching. She stopped, sniffed around suspiciously, and got back in the box to poop even though she had just finished using it. I KNEW cats saved it up for fresh litter!