Pet's place position is not reset upon exiting an instance.
Last night I was running Ifrit Hard Mode and Amdapor Keep as my Scholar. I frequently place my fairy pet near the tank for healing etc. Upon completing the instance, exiting, and re-entering - the pet will still attempt to go back to the position it was placed in last. Exiting the instance does not reset pet behaviour.
This resulted in a complete (and hilarious) wipe as my fairy began walking to Ifrit and aggro'd him, to which he responded by breathing fire all over us. Later in the night I re-entered Amdapor Keep and immediately my fairy ran up the stairs without any command being given, aggroing the first pack of lunatic priests along the way before withdrawing. I can only assume it was attempting to go up to the third floor.
I can see how keeping some pet behaviour through instances/zoning would be beneficial, such as Obey, but having the pet try and walk back to its last directed position can cause some issues aggroing enemy monsters.