I have two bottles of M-Sten. I just started my cycle today actually of one that is clearly dark orange. Expiration date 9/15 lot:418. My second bottle came in today (decided to stock up on it) and the expiration date is 3/14 Lot 31105 and this bottle is much lighter orange. Almost gold. Two questions, should I be concerned that it is expired? AND why the obvious difference in color?