Guild Wars 2

Hi there,
my guildies and I just completed the aetherblade retreat dungeon yesterday evening, and I’ve realized that while they all got the achievement for it (cornered, caught, collared) I, surprisingly, didn’t.
We all did the dungeon from the beginning to the end, without any deconnexion or without ever leaving the instance. The only thing I could think of is that when Horrik fell I was on that aircraft with the cannon just looking what it’s all about, but since I had my pet (I’m ranger) reducing Horrik’s health during the whole fight and I did hit him a few time before rushing onto the aircraft I believe I got the contribution for his kill.
I think I’ve noticed an achievement notification popping on the right of my screen when we completed it but I can’t remember what it was.

I could care less since it’s only 2 achievement points and I’ve got my mini Horrik anyway, but well, that’s still a bug.