I've been trying out the "friend" in-game chat feature to talk to someone I know who bought the game, and I've noticed that sometimes I don't see the messages he sends me until I type one of my own, then I get all the messages he's sent me since my last message at once. They have correct timestamps, so it's like they're getting stuck in a queue of events to process, but not being processed until I send a message of my own.