Simple move this line of code. (Located in tracker.lua in addon recount folder.)
 = 10, -- Blood Shield
From the local GuessAbsorbSpells =
To local AbsorbSpellDuration =
Just make sure you drop it where all the other death knight spells are listed. (Not really sure if that even makes a difference I'm no expert on lua or modding the UI.
Many DKs including myself have always wondered why it wasn't properly taking into account the absorb from blood shield mastery.
Also have a screenshot of the updated details.