Are weapon mastery feats intended to be *class-specific* multiclass feats?

[Dice4Hire]

Whip Training’s requirements are as follows; Prerequisites: Dex 13, any martial class

Page 208 of the 4e PHB says “A character who has taken a class-specific multiclass feat counts as a member of that class for the purpose of meeting prerequisites for taking other feats and qualifying for paragon paths.”

Fighter is a Martial class, and as such the Bard multiclassing into fighter should qualify for Whip Training.

I would tend to agree. The feat says 'martial class' not 'a class using the martial power source'. Some abilities say clearly power source, like the Sorcerer's extra damage ability, which says 'any arcane power' as opposed to 'any sorcerer power'

That is clearly a power source. The feat is not.