Health bar dropping whilst sneaking.

Swindy

Whilst sneaking pretty much in the middle of BFN, not in action, no hostiles even within bow range, etc...I've noticed after the patch before last night that my health bar drops once I cease movement, ala if it were the stamina bar.
It happens in different places for me, this one was sneaking up towards, & consequently whilst sneaking all around, Crooked Finger Redoubt.
Once I cease movement, the health bar drops about 20% (buffed with food and Pact buff campaign bonuses), then slowly regains, in the same manner that stamina does.
In these circumstances, the stamina bar does not drop the same amount as the health bar does.
It was happening the other night in IC prior to this latest latch also.

It's rather confusing, if anybody or Zos can enlighten me.
I've not bothered with a support ticket yet.