Checkmate without knowing it

Ha it goes to show you how bad a chess player I am in that recently I won some matches with a move that resulted in checkmate but I didn’t know it at the time! My latest granted I was playing on my phone (not the best advice) , but I am willing to admit I have won matches not knowing until it said congrats 

I had an online tournament game where I was running really low on time and started a line with a series of checks and when the game end dialog popped up, I thought I had lost on time, but had checkmate instead. 

Mine was even better. I unwittingly checkmated my opponent when I "forked" the king and the bishop with a knight check, intending to win the bishop but lose on time with three seconds left on hand.

I’ve checkmated my opponent whilst executing a fork, expecting to win the queen.

This happens to me quite frequently.

it should not happen, we should be seeing the "check" as mate