We had a bad case of fleas 2 years ago, so I stocked up on Capstar. Didn't have a problem last year-don't think I used it once. I saw a flea on Sammy the other day, and I saw a flea on one of the cats. I broke out the Capstar, and noticed it is past it's expiration date-drat! The ones for the dogs has a date of 11/11, and for the cats, I think it is 9/11. Do you think if is safe to still use them? And if so, will they be effective at all?