Checked the SKCC page late this evening and was browsing the comments, and one guy in MO posted "Our signal is back on 3549.98". I was curious so I tuned in there and sure enough I heard a dasher of sorts - a short dasher every 5 secs or so. Rather weak, some qsb but consistently in there. I asked him how long he had heard it and he said he had it 40 minutes earlier, then tuned off to do something else and came back and it was still there. Also reported hearing it "sometime last week".
This was very beacon-like, not a guy on a key or keyer. I listened for maybe 10 minutes before it went off the air around 0550z (or simply faded out altogether).
I hear things from time to time on the ham bands which make me stop and verify that I'm not hearing things (things that sounds like beacons but aren't) - however, as this was heard before, I'll check this freq from time to time. BTW, 3550 KHz is also the SKCC 80M calling freq.