Spells: Charm Guard Issue

[Sunnyvale]

I'm not 100% sure what causes this but when I tell my charmed pet to guard it occasionally will walk back to its original spawn point as opposed to staying where I tell it to guard.

I have been randomly trained in Sebilis a few times after my pet disappeared and I couldn't figure out why, until the other night I finally saw it start walking back towards it's spawn. This only seems to be an issue with guard, and it doesn't happen all that often (maybe once per hour or so).