I don't know, on one hand, a week seems kinda quick, like maybe something unexpected popped up on his end. But then again, he's logged in, and stuff happening is no excuse for lack of comms. I would let him know that you are about to pursue a -1 for his lack of comm, and see if that doesn't snap him out of it.
I would send an IM stating something to the effect of "...Negative feedback will be posted in the EE unless you respond to this within xx hrs." I'd probably give him 48 hrs. to respond and watch whether he's logged in again to see if he got the message. Just my $.02 though. Good luck buddy.,