Whilst using my trident killer mob farm, I have noticed that on kill of some the mobs, the experience rolls toward me but hovers about at my feet rather than being absorbed. 

I am unsure of the circumstances that produces this as most of the orbs are absorbed. I have a suspicion that perhaps the experience somehow falls into the hoppers perhaps (is that possible at all?)

I have attached a screenshot of the orb hovering around my feet, I can actually walk around and it follow me. 

The other screenshot shows the setup of the area in which the mobs fall and are killed with the trident killer (when it works...there is another open bug here after all!)

Please let me know if any further info required