I've gotten a message like that (no idea if it's the same or not since I can't read Japanese) a few times trying to send messages while in-game in a high-receive, laggy area (i.e. lvling in Crawler's Nest on a busy night). I did a bit of looking into it because I got freaked out, too. Seems it was just a system error glitch. The system was trying to tell me that the message was NOT sucessfully sent, but presumably the area's lag made the system send me the Japanes version of the error message. This was over 6 months ago and I've had no discernable negative effects from it. I can only assume something similar happened in your case, and, if I were you, I wouldn't be too worried.