My parents have always had dogs who would routinely skip a meal and it's no big deal. However, I'm with Bev as far as my current two go: if they aren't inhaling their food, I'd be on the phone with the vet. Mine even want to eat if they just threw up, like, 10 seconds ago. When we brought Maddie home from her spay surgery, she was very groggy and sore. She did not want to stand and did not want to walk, but she wanted to eat! And did eat, lying down in her crate.
So it depends on your dog. For some dogs, skipping a meal is nothing. For other's, it's a big warning sign that something is wrong.