Seems like something pretty common (or so I've read)... it's like she gets nauseous and tries to make herself barf when she hasn't eaten in a while. Happens sometimes in the mornings before breakfast, sometimes during our afternoon walk before she eats dinner. I think there are theories out there that it's like...too much bile that needs to be expelled, or something.I wouldn't worry about it unless it lasts more than a few days.
Except what's "the empty stomach barf"? The only thing that makes my dog gag is eating grass.
Willow always eats grass anyway, regardless of how hungry she is, but yeah a couple mornings ago she didn't want her breakfast, I put her outside to pee/poop, she immediately ate some grass and then barfed the bile. Generally I'd say she only does it a couple times a month. But yeah, it's weird.