My champion used a random mastery page that doesn't even exist among the mastery pages on my account

I basically noticed that when I got +1 gold for minions I didn't last hit, which would be weird, since I played ADC. When I went back and checked, I didn't even have a page with the mastery that grants gold for minions dying and then the next game I noticed I also got 5% CDR which the rune page I selected for the game doesn't even run.

This is 26 levels of WTF and I'm mostly pissed because this happened to be in games 2 and 3 of a promo series which I was essentially forced to play with absolutely garbage masteries and apparently a rune page too.