I had some DNS issues last week because I forgot to renew my domain name registration. According to my FeedBurner statistics page, one of the consequences of this lapse on my part is that I've lost about 1,000 subscribers to my feed on Rojo. It looks like they may have decommissioned my feed in their service once the domain name stopped resolving after a couple of hours. This seems like a reasonable thing to do.
I've sent some mail to the Rojo folks through their feedback email address but don't hold out much for ever getting a response. It may be that there is nothing for them to fix since the relationship between my feed and the subscribers may have been deleted from their database once my domain was considered to be gone.
Anyway, if you are a Rojo user wondering why my feed disappeared from you subscription list, now you know.