Chocobo HP Boost?

It's bugging me so I feel I have to post and ask people here. I leveled up my chocobo earlier today from rank 15 to rank 16 and its HP shot through the roof from 2200hp to around 11400 hp. I was very surprised. My Job level is 60 but now it can actually kill mobs on its own which is very useful. Up to this point whenever I played in parties with other players with their chocs out their HP was similar to mine on my screen but now (and I have tested) they also have much larger HP's and can kill mobs way easier. My Choc has full Healer and Attacker and 2 skills into Defender.

Is this a bug, known issue or have I missed something?

Once the chocobo hits level 51 with you, it jumps in hp to match the initial equipment of that level.

My chocobo at rank 20 level 60 has almost 13k hp.

It's to account for the gear curve. Chocobos don't scale with our iLvl, so there has to be a high curve for him to keep up.

Don't worry, he'll be crap again by the end of the expansion.