Yeah my question was more like why did this happen? it's not like my node or this peer were out of communication. Like I said we were communicating fine, even forwarding several other HTLCs. I have like 13 routing events with this peer since Jan 13th. And I saw this stuck HTLC for several days before the force close, I was afraid it was going to happen. It seems more like a bug.

Also by analyzing the structure of the transaction, I can see that my output is the to_remote (unencumbered one). So why the extra transaction, is labeled as a "sweep" by RTL but I was under the impression that only the to_local needed a sweep. So this other tx makes no sense to me.