I am so sorry you waited such a long time for an answer. Sometimes dogs gulp because they feel nauseous. But a thought is also hat she might have the feeling of something stuck in her throat. Does she chew at anything? Rawhides....toys, etc? Those rawhides are downright dangerous in my opinion. I remember a dog of mine once literally choking on a large piece he was trying to swallow, and I had to reach in and pull it out of his throat. It could have killed him.
I guess by now, either she is feeling better and it passed, or you did take her to the vet. I know the "wait and keep an eye on her" reply from a vet is always frustrating, but it is wiser when a dog is not behaving normally, to take them to be checked anyway.
I hope your dog is okay now.....