Received "bounty expires in three days" message too late

On my question War of dots: simple RTS war game in python, I placed a bounty for 50 rep, then rewarded it to one of the answers. When the first bounty was 3 days from expiry, I got the message notifying me on the fact, perfectly normal stuff. I never observed the message telling me it was one day from expiry because I rewarded it before then.

Immediately after rewarding the first, I placed another bounty (this time the lowest rep I could choose was 100, so I chose that). When the second bounty was 3 days from expiry, I never got a message saying it was 3 days from expiry, not complaining as I reload my tabs daily anyway. But, 9 hours before, I should have gotten the "bounty expires in one day" message, I got "bounty expires in three days". What???

I did end up getting "bounty expires in one day" on time, and at the time of posting, I observe this: