I ran into this a few times in the long ago past and the IMMs gave a warning like this to break it up. In the end, they were cordial about it and allowed us to group together over time. What they did warn us about was that if we were doing it often or weren't communicating in game enough, then they'd revisit the conversation. If it were me, I'd simply just go by this advice and make sure you're communicating and not exclusively grouping with said person. I'm guessing that the same IP thing is a coded flag. One meant to stop perma groups.