I get no warning of my friend having gone offline, nor is he offline when I check my friends list. Because of this I then have to right click a previous whisper sent to me, or go to my friends list and whisper again, sending the same message with no problems.
I can usually whisper with no issues at all but sometimes this bug will repeat itself every other whisper for a solid 10 minutes. If you want to look at previous chat logs I can certainly provide character names that this has occurred with and rough timeframes, would just prefer not do so over open forums so let me know how to contact you, or contact me if you need more information. Thanks for the time and great game, had 0 issues outside this minor annoyance :P