We were doing A12S and our DRG put on B4B right before getting killed by Mega Holy around the 4:40 mark. FFLogs shows his B4B lasting practically forever.
You might notice my (NIN) b4b around 4m lasting an extra long time too, but that one is actually correct. I put on B4B right before the Temporal Stasis mechanic that freezes buff and debuff timers. However, that mechanic was over before our DRG put up his B4B so this is a separate issue.