I can confirm that I saw the following characters /walk up to the followed character.
BUT! This appears to happen only one time. Afterwards the characters move basically as they should.

I did not 'loose' any of them while riding about on epic mounts through shattrath or flying with my 60% gryhons.
I did not encounter any negative effects while doing the new 'kill 20 ogres' quests and was basically allways moving and then casting.

I tested this yesterday after midnight on my EU server, so after peak time. This may be a latency issue or a cosmetic change about the follow mechanics.