Help! My pup won't eat!?

I am leaving on Vacation today and my 4 month old Shih Tzu, Sadie, decided to NOT eat at all today. Normally she devours her food. We've been packing and really have been tense about leaving her for the first time. My husband and I are wondering if she picked up the vibes and knows something's up? We're going away for two weeks, while she stays with my mother in law and my mother. She drinks water, plenty, is playing with her toys, and she actually ate a cookie bar of hers that's usually a treat or desert. But she won't eat her actual food! I even opened up the other flavored food and nothing. I am worried since we'll be gone for so long. Help! (it's a first dog for both and a first time leaving her)