New feature?

The other day, I was running around on a new druid in HC, suddenly the screen freezes (even though network is up and working fine), it's fine though - since GGG servers handle this fine, right... right?

Well, the "Unexpected disconnection occurred" came fairly quickly, it's fine, I can get back in and continue where I left off. Wrong, my guy is now in standard league as I click log in and observe my list of characters. Pretty miffed at first, but what can you do.

Fast forward to today, I'm in a party with a guy, we're clearing some mobs before a boss, suddenly I see the following in quick succession:
XXX has been slain
XXX has left the party
XXX has gone offline

This was *instant*, so I went over to where he supposedly died, and there were nothing there that could hurt the guy, no traps no nothing (even if there were he could easily soak damage and not die). So, is this a new feature and something to expect going forward - some good old surprise mechanics? You're doing well so we're just killing your character?