Damage shields hitting when a mob strikes you

[BWStripes]

I was testing resistances on a 70 warrior, so, wanting to test druid spells, I zoned to Southkarana where Grizzlenot is.

I stand here, immobile with my back to the mob, and I get:
[Sat Aug 18 13:18:59 2007] Grizzleknot tries to crush YOU, but misses!
[Sat Aug 18 13:19:03 2007] You are surrounded by a thorny barrier. You have taken 9 points of damage.
[Sat Aug 18 13:19:03 2007] Grizzleknot crushes YOU for 11 points of damage.
[Sat Aug 18 13:19:03 2007] You are surrounded by a thorny barrier. You have taken 9 points of damage.
[Sat Aug 18 13:19:03 2007] Grizzleknot crushes YOU for 15 points of damage.
[Sat Aug 18 13:19:07 2007] Grizzleknot tries to crush YOU, but misses!

I can't tell if this is actually true at the moment because of his regen, but it looks like every time the mob strikes me, it gets a DS bonus.

Hope this isn't happening to players as well, or powerlevellers will be having a whale of a time :P

[BWStripes]

Forgot to mention, running 1031

[BWStripes]

I should have been clear - the DS is on the MOB not the warrior :p

[Theeper]

It doesn't look like you get the extra damage each time you get hit, nor on each swing. Is that just a proc or a spell ?

[BWStripes]

The warrior is fully unbuffed, has attack off and is standing with his back to the mob. The mob is a druid caster, has buffed itself with a DS, and is hitting the warrior.

I am getting the above DS messages as a result of the mob hitting me.