1-cost unit charged me 3 gold

(Unfortunately I lost and was booted from the game immediately after buying the unit, so I didn't have the time to nab a screenshot).

Saw a Kassadin being offered. Bought it. Got 3 gold taken from me.

I only had 1 other Kassadin at the time so there was no combine cost-related bug, as has been reported elsewhere. Hovering over the Kassadin on my bench showed it as costing '3' but with the silver colouration of a 1-cost unit, instead of the typical blue of a 3-cost unit. My other Kassadin still had 1-cost listed in its hover info.