A mistake and a quest
[King tier beast killed]
[Congratulations, you are now level 32]
After getting the last hit on the king tier beast, the message was all he needed to confirm the beast was dead. Quinn had already levelled up once from his multiple quests hunting intermediate beasts. The experience requirement kept getting higher, but he would often get bonus exp for defeating a beast for the first time. Even more, if it was the first time the beast had been killed by anyone.
It was the same this time, Quinn actually didn't receive an instant level up quest when using his inspect skill on the beast. This meant that even if he killed it, he wouldn't have been granted a level up. The reason why he levelled up, was due to the bonus exp as well as the leftover exp from the quests before.
In a way, the system was telling him that a King tier wasn't as much of a challenge as it was once before.