Its not normal for most dogs. He could have issues with reflex. I have a 12 yr old dog who has been throwing up a couple times a day since he was 4 months old. I had him checked out by the vet and there doesnt seem to be any reason for it. Just keep an eye on him and make sure that there isn't any serious issues going on like throwing up blood. As long as the dog is healthy and happy, he should be fine.
Hope that helps.
Hope that helps.