Hextech S grade chest message

So I played a game and got an S- on a champion, I waited a bit in the lobby because I was talking to people. Waited a little bit before starting my next dynamic que, even had some time during the searching for game que.

Well as soon as the accept screen pops up my reward for getting an S also popped up simultaneously and blocked me from accepting, by the time I got the message away the time to accept was like 1 second.

How could something like this get through PBE testing?[zombie-brand-facepalm]