I'm an on-line gamer and get that all the time. It's to keep a player from spamming, but it's highly inconvenient when there's a battle going on and I'm trying to coordinate troop movements!
Anymore, I think it's a standard that some Boards can and do turn off. It just didn't catch up with this Board until the upgrade. it does make it difficult to respond to many messages without taking a sizable chunk out of your session...