I've been listening to K4M from my desk at work (via skype to my rig at home), and I'm hearing the op send some very high-speed CW (I think) interspersed with the normal QSO traffic. It always seems to be at the end of a QSO, and I've only heard it on 20 meters. An example: listen
I isolated just the high-speed part: listen
and slowed it down 4 times: listen
It sounds to me like he said "SD5AE". Huh?
And on 17m today: listen
Just the high-speed part: listen
Slowed down 4 times: listen
That one sounds like "RL-R"