I don't recall it doing this before, but recently my P-quill is capping at 100 HP for both tier 2 and tier 3 pets... Anyone getting this?
Are you sure that it is only healing 100 HP? Last I knew, the percent sign wasn't showing up for any of the percentage-based stuff, so you'd have to pay attention to total healing to see if the P-Quill is healing 100%.
(Disclaimer: It has been a while since I've actually paid proper attention to the icon/percent stuff so they could have fixed it at some point without me noticing.)