Champion Mastery Grades

So a couple days ago I was with a friend playing some Normal (Blind Pick) matches and I got an A+ with Yasuo and won, however when I looked under collection (I am on the new client) and then hovered over Yasuo, it said that my season highest grade was a B. Not only did this bug/glitch happen with Yasuo, but happened when I used Veigar aswell, however when I was playing Veigar, it was a Normal (Blind Pick), and I lost that match.. I went 22/4/12, and got an A+ with Veigar but when I looked under collection, it said that my highest season grade with Veigar was a B+. I have screenshots for proof below. http://i.imgur.com/tGla3wF.png http://i.imgur.com/T2MFVRc.png http://i.imgur.com/iqYTOGi.png http://i.imgur.com/Efyz6et.png