Endermen only kill Endermites that spawn from ender pearls

DISCLAIMER: I don't know if this actually is a bug. This is the first bug I have ever reported.

I threw an enderpearl in the End and it spawned an Endermite. That's normal, I know that... But the Endermen around me started attacking and killing the Endermite. I thought, "Will this also happen when I normally spawn an Endermite with a spawn egg?" So I spawned one, but the Endermen completely ignored the Endermites that I spawned using eggs.

I don't know if this is normal, and I want you guys to know about it.

This video was recorded in 15w33b, but I have noticed it already in 15w32b and c. (One Endermite escaped and you see two Endermen run after it, but I suspect it's just their natural AI that sent them there. They don't attack the Endermites at all.

How to recreate:
See video.