I can't imagine it'd hurt to air them out a bit and maybe add in some new cedar. You could also try setting up another small tupperdor with less sticks and seeing if it carries over. Neither should be necessary but it might help. The only causes I can think of is cheap sour processed tobacco finally showing its true colors or cigars going through fermentation. You normally get ammonia but Ive smelled all sorts of weird aromas coming off fresh sticks. Have you added any new stock recently?