what is interesting is that it's a level 85 quest listed under "quests" and then "raids" which may indicate that it's a quest given and/or completed within a dungeon or raid. it looks pretty incomplete so this may change before the patch is released.
in an attempt to find out more and possibly run into this new quest on the PTR, i tried to complete the lashtail hatchling quest chain on my premade druid. unfortunately i got stuck at the "be raptor" part and am unable to complete it. it may be due to me missing something during the quest chain, phasing issues or because ZG was officially turned into a 5 man dungeon, but that specific quest is bugged on the PTR and there's nothing i can do. literally. when teleported into zg to play as the raptor, i find myself zoning into an empty area that i can simply fly through.
note: to be on the safe side, if you haven't completed this quest chain on live servers, i would recommend doing so before patch 4.1 hits. once ZG becomes a new dungeon zone, it may cause a whole host of phasing/quest chain problems. if the lashtail hatchling does indeed become available as a true vanity pet, this quest chain may become a prerequisite and if phasing is this huge an issue, doing the quests before the patch goes live will be the best way to avoid those issues. (on the other hand, doing the quest chain prior to patch 4.1 could just as easily cause phasing and completion complications. :\ so it's a risk either way.)hopefully someone who has a completed the quest chain can provide some insight on whether or not the "an old friend" quest pops up for them while in ZG or doing some of the new ZG-related quests.