Folks have already mentioned seting up your own gear and checking your tanks, but there is one other thing I do that would have prevented this problem and one thing that concerns me that no one has mentioned.
I check both tanks while we're still at the dock. I don't assume there will be extra tanks on board (there usually aren't) and if my tank is low, it either prevents me from diving or shortens my dive. Before we leave the dock, I make sure I have two full tanks.
The other thing I was wondering is, FLTRI, where was your buddy when you surfaced with the DM and returned to the boat? Was he now diving solo? Did you not have a buddy? Did anyone have a buddy? Were you all diving solo in a group? Being in a group does not replace having a specific buddy.
I check both tanks while we're still at the dock. I don't assume there will be extra tanks on board (there usually aren't) and if my tank is low, it either prevents me from diving or shortens my dive. Before we leave the dock, I make sure I have two full tanks.
The other thing I was wondering is, FLTRI, where was your buddy when you surfaced with the DM and returned to the boat? Was he now diving solo? Did you not have a buddy? Did anyone have a buddy? Were you all diving solo in a group? Being in a group does not replace having a specific buddy.