Players coming off bench

[ChuckS]

I had 2-man, BV tonight. 4 minutes to play in a hotly contested game, I am T, tableside. My partner and I simultaneously call a held ball in the lane, and I come running in when I see A1 and B1 are not letting go. They continue to fight for the ball, and it gets a bit heated with all players milling around, and we restore order. He calls a double T on A1 and B1. He then asks me if anyone came off the bench. I said "I did not see anyone come off the bench", mainly because I was not looking there. I have had it drilled into my head never to turn my back on the players. So....was my partner supposed to observe the benches, since he is facing that direction, or me?