This March I reported to peering@ a similar problem to RR1
If this was happening in March, the "good" news is that this is not due to the new route servers (different OS, BIRD upgrade, new config, etc.).
I looked at the BIRD release notes, and I'm not seeing anything about BFD specifically. There are plenty of mentions of generic bug fixes.
I suppose I should take this to the BIRD mailing list.
-- Richard