I've run into the same problem...I'm 5'3". "Regular" length stuff is often too long on me.

Brands that offer bonafide Petite sizes include Hind, REI, Marmot and Moving Comfort. Don't know if any offers a nylon pant, but all have black tights or looser-fitting "track" pants. I think InSport might be another one.

You might check out some of the runners wear supply places on-line. Plug in the word Petite and see what pops up. Good luck!