You can UNDO Ornn upgrades

I noticed this recently when playing that if you accidently click 'UNDO' when in the shop menu and Ornn has upgraded an item for you, it reverse the upgrade and you can't be re-upgraded.

I did this after I sold my Zhonyas on accident when I went to sell refilling potion, got my Rabadon's upgraded, then clicked undo to get my Zhonyas back. This is a HUGE problem.

Also why does Ornn upgrade randomly?