I was there last night, 131W and tried all the DC transponders and found that none were open then. Could it be different today? Most certainly!!
If my memory serves correctly, I think I recall seeing something about them being open yesterday. If so, it was not long lived. Sometimes they come and go like greased lightning. But, still fun to go looking for.
EDIT: Just went tried 4020 and I can't even turn up an active transponder there. My memory isn't what it used to be, but I think I had the same thing last night. Just tried another transponder there that is DCII and got a lock on the transponder, but nothing open, so that means either 4020 is gone or is dialed down to low on power for me to see it.
EDIT-EDIT: 3828 is one that my 6000 won't do, nor anyone else's for that matter. Seems to be something the firmware.