@Niemand : In the first chapter he reacts badly to the other younger and cokcier guard calling the MC a mud hunter. My guess is he has been on the job for quite a while and knows a bit about the Mc's background, potentially including why the Mc was hunting solo for years.
@SunSun : Yes it is
@RC21 : depends on if the reward is for the kill (like the goblin ears) or the usefulness of the material. If it was a valuable material, I can see the Guild asking him to use it over and over. Heck it would not surprise me if there was a note somewhere from when he joined saying to look for signs he had maxed his skill, and just forgotten about after 2 and a half decades.