Changes in Health Regen??

My main account was used to need about 5.40 - 5.45min to regen the next hit on EB when his health was down. With the current Epic Boss (Black Forest Witch Returned) he needs between 6.05 and 6.10 min.
There are no changes in my health regen bonusses, so I can not explain this change (which is really bad when you go for 150 bosses)

I know from at least one member in my guild who has the same problem. Has there been made any changes??

Would be great if someone could look nto this, thx