Pet switches to "Follow" after an intrazone gate.
 

I keep my pet parked at my kill spot and use gate for long distance pulling. After gating, the pet switches from Guarding to Following. Not sure if bug or feature.

I learned this the hard way after my pet aggroed all of WW.

Moving to resolved due to lack of research.

I've noticed this as well in ToFS. Instead of killing pet before mirror I planned on putting pet on guard then summoning him via spell to prevent pathing agro of the mirror. I've noticed that after going though the mirror the pet will follow regardless of being on "guard" and cause pathing agro.