The important question...Did you finish the game?
I've seen enough close calls by batters that are oblivious to what's going on around them that I've got into the habit or making double sure the batter knows I'm there when I sweep the plate (can't say that I've ever worked a game with a mat before).
I'll make eye contact with the batter to see if he realizes I'm there, hold up a "stop sign" to him (like the "do not pitch" signal) to get his attention and sometimes even say something like, "Don't swing your bat now".
Knock on wood (or aluminum or composite), I haven't been nailed yet!