Only one way to know...get a test before AMPS...find out where he's at around 8+, if he's running low he could have some medium carb food to give him a little boost so he wouldn't keep going down and missing his shot.
If you're going to be home and can monitor, it would be good to try to get his insulin into him.
Did you stall/test again this morning? To see which direction he was headed?