Any chance another host took over the address of your cpu? I just brought up another machine's /net interface with the same address as another (e.g. two machines sharing 192.168.1.103) and got this same panic. In this case (5 drawterm 0x000a0715 exportfs + 1109) it is a garbaged 9p message.
Running 2012-12-21 : d51dc9b833d7 I get a similar looking error. When I don't shut down drawterm before do something that changes my ip address. Go home at night for example. I see drawterm has crashed with a SIGILL Exception.
This issue can be addressed as we roll in updates from the linux branch. There are a few conditions like this where the crash log doesn't really help. We know that the connection went away, no need to dump the stats.