This is just a Theory at the moment. I have no proof other than my reputation here and the fact that I was completely dumbfounded.
I was remote connecting through my computer at home through "Log Me In" it has some input lag but other than that I did nothing in particular.
Here is what I did and what happened.
1. Opened AH
2. Switched to RMAH
3. Clicked on Auction Tab
4. Clicked on Sell tab
5. Clicked on gold icon to list maximum gold
6. Hit Sell
At this time I got a second of lag and all of a sudden in my 3 pages of inventory there were at least 10-20 stacks of "square topaz" in each stash. The weird part was they were overlay-ed ON TOP of current items in my stash.
I couldn't take an SS but it doesn't take much imagination to picture how little sense this made. Stacked items on top of other stacked items not lined up in the "real" stash squares.
It's as if a bunch of gems from nowhere were deposited in my stash upon selling gold on the RMAH. If there was some way to reproduce this with different gems/items it would be amazing.
I did my best, hopefully someone can try to reproduce.
TLDR: I sold some gold on the RMAH without doing anything else or searching. Upon selling about 60 stacks of square topaz showed up in my stashes (all 3) ON TOP of all of my other stashed items. I could click and sell them. But they disappeared after leaving the AH.