My pet paladin (lvl 60) has no mercenary. Everytime she zones or logs on I get the yellow text saying: "you no longer meet the requirements for this mercenary!"
If your all access expires while a journeyman mercenary is up, it does this. It removes mercenary because you do not meet requirements, but its more like a temporary suspend where it keeps trying to bring it back up when you zone. Get an apprentice mercenary and unsuspend/suspend it will clear the message.
With the message it reads more like no mercenary unsuspended. When you have one out and go free to play that is the message, I've had it before.
Mercs sometimes give weird messages for no reason, occasionally I zone into a raid zone with no merc up as you can't when your in a raid and it tells me its suspending my mercenary.....it was never up!