Wrong Masteries

Played a game earlier today where I was playing Anivia mid. I made a mastery page in champ select and equipped it (I normally do this the page I made was 12/18/0). Once the game starts loading I see that I have the strength of ages mastery which I did not chose. Obviously my first though was that I chose the wrong page so I went and checked what masteries I was using on lolnexus I was running 12/0/18 with expose weakness which I never have used so I thought that was odd and so I thought hey it must have been a page I forgot I made. But then after the match I went and checked the official league of legends match history and all 20 of my current mastery pages. none of them matched the masteries I had that game. Also the page that was selected was my 12/18/0 page. Just thought this was odd not sure how it happened