Homunculus question/report?

[Serenity]

I'm having trouble with how my homunculus is gaining experience. It is currently level 42, so to reach the next level, it needs 372510 exp points. I'm trying to level it at leaf cat, which gives 6060 job experience each. According to my calculation, the homunculus needs to kill ~62 leaf cats to gain one level. I'm checking its statistic window and for each kill, it only gains .2% (which is the round up figure if you divide 6060 by 372510). Am I missing something or is this a bug?