Not a Bug Holy Symbol Bug?!

So I've witnessed an interesting phenomenon.

If you damage but not kill a monster while under the effects of holy symbol, and then your HS is rebuffed, it seems that you get the original HS buffed exp of the monster + additional exp, which is dependent on how much damage you did to the monster while you were under the previous HS.

In my reference pics, EXP gain with HS and 2 members in a party is 5455 (solo EXP from Galloperas are 5000).
However, when I have hit the mobs a certain amount, received HS again, and then killed them off, I've received extra EXP, such as 5835 or 6090. I even saw 67xx.

Not sure if this is a systematic bug that's integrated into v.62 MS itself, and I don't think its game breaking as you would have to time damaging the mobs 90% before receiving an additional HS every mob to "abuse" this, but still intriguing.

My most sincere apologies if this was a known/deemed irrelevant theme, I saw 1000+ resolved Bugs and gave up.