Your first instinct about a nutritional deficency is probably a good one. After all your cat was recently pregnant. Pregnancy typically depletes the animals reserves of fat, muscle tissue, and bones. Everything that your queen eats has to be shared with her kittens. Inside the womb and then during nursing.
You may want to consider adding a supplement like Felavite or Nutramalt to your queen cats diet. You could also feed a high quality canned food such as Nutro, Science Diet or Eukanuba in addition to the vitamin supplemt. Pica, a type of eating disorder that prompt the sufferer to eat non-edibles, is most commonly associated with a vitamin, mineral or combination of vitamin and minerals missing from your cats diet. Particularly, potassium and calcium (these line mammalian nerve cells) and the B vitamins. Icreased dietary fiber helps some cats who may respond to access to greens i.e. wheatgrass, barley grass, alphalpha sprouts, etc.
Pica is a condition in which cats may try ingest something besides what is considered food. Examples of pica would be licking paint or eating dirt.
If after six to eight weeks of feeding a well balanced diet with a supplement you still see this whisker chewing behavior you might want to consider that it is a more generalized form of pica. In some instances medications for obsessive/compulsive behaviors such as clomipramine -Anafranil Rx, or buspirone - Buspar Rx (my favorite) may be helpful. These medications will take four to eight weeks before the cat begins to feels some affect.
Some people feel that consistent punishment will work but this can damage your relationship with your cat, and I dont recommend punishing a cats as an effective form of behavior modification. You might try at that time painting your kitten's whiskers with apple bitters (sold OTC at Petsmart, Petco and the like).
Make sure that queen and brood alike have plenty of diversions in the form of toys and scratching posts.
Key word: Nutritional Supplements and a Balanced Cat Food and Greens, Greens, Greens Keep us posted.