Just what it says. Clicking the sell button will sometimes cause your champion to cast their q. It doesn't really appear to affect the gameplay, since it's in fountain, it's just annoying.

-Repro Steps:
-Open shop
-Sell something with the sell button while your champion has q learned.
-Thats all.

you may have your shop right over the UI, so the sell button is over your first skill UI button.
Try moving the shop elsewhere

Something similar happens to me sometimes when i click the right side of the buy button, because i have it right over the ping button on the minimap... people yell at me bcs of that xD

I am currently addressing this bug. Thanks for the report.