This actually happened to me today when I was doing Garuda HM farm.

First time it ever happened she just wondered off. I think it had something to do with regen before I pulled.

I never actually appreciated the usefulness of Provoke as a tank until PLD became my main instead of WAR. If you find yourself losing hate you can provoke, tomahawk/shield lob and get hate back.

When you do Garuda HM as off tank or solo tank provoke will allow you to grab the adds with huge range (25y - same as BRD Skills) without breaking a sweat.