Client bug in ARAM - accidental rerolls

You seem to be able to accidentally hit "reroll" even when you don't see it by hitting the wrong place to exit out of mastery / summoner-editing popup windows. This is really bad.

Twice now I've been really happy about the champion I get, change masteries around for it, and as I exit out, I'm like WAT I DIDN'T REROLL! D: as I lose that champ (and get reksai). only happened with the new client ofc.