Lower Priority Queue Wait timer restarts if missed the accept button.
I think riot should probably consider that people just waited 20 minutes to play a game only to miss the accept button for a match and wait another 20. I see how it could be taken advantage of if waiting 20 minutes would end the queue completely but maybe if you miss the accept after waiting the 20, give the person a 5 minute gap in which they can rejoin queue without the wait. If the person misses the accept and logs out, it restarts.