Guild Wars 2

I helped my friend kill King Toad today, while we were in a party and it didn’t unlock World 2 for him. He started the instance. Is this normal behavior? When we defeated World 2, Zone 2 together, it unlocked Zone 3 for me.

Did he he stay and got ported with you to the bonus lvl or did he leave before the clock had run out?
Also did he get the achievement for beating the lvl?