Not sure if your "dits" reception is the same, but go over to the HF Beacons part of the forum and check out the entry titles "Dashers / Ditters 5 December" and see if this jives with anything you heard. Apparently, there are a LOT of them out there.
I can't help but think these are very intentional - propagation beacons, I would think. These guys are not hobbyists!
In fact, that might be a better place to post your findings, as what you heard was very beacon-like, and others there might have more info for you.