The chops only need to marinate in the mustard-herb rub for about 30 minutes in order for the great flavor to permeate the lamb. If you want to go longer than 30 minutes, or even overnight, that's fine, too.
Combine first 5 ingredients in a small bowl; stir well. Rub mixture evenly over both sides of lamb chops. Place chops on a baking sheet or platter; cover and marinate in refrigerator at least 30 minutes.
Place chops on grill rack coated with cooking spray; cover and grill 8 minutes on each side or until desired degree of doneness.
Note: To prepare indoors, place a grill pan over high heat until hot; coat with cooking spray. Add lamb, and cook 8 minutes on each side or until desired degree of doneness.