It's hard to piece together exactly what happened, but my instinct tells me that this is working as intended. This code hasn't been touched in ages and this is the only report I can remember about quota problems. I will say it's odd that it was reported at the same time by a few different people though.
Can the people that were affected clarify whether this has continued to affect them or whether they were able to send once the time mentioned had passed? It would also be useful to know the exact message (the important part is how long until you can send again) and exact server time (from the top left corner of the screen).
Also note that quotas are measured per-ip, not per-bot, so if you're sending bmails from multiple bots, you can hit the quota more easily. The current limit is 3 per 60 seconds (i.e. the 4th one will get blocked).
Also, a friendly reminder that off-topic posts don't belong in this sub-forum. I cleaned up this thread a little.