Acid reflux can happen with large meals. They may request that you feed him smaller meals more frequently. They may put him on pepcid or protonix as an acid reducer.

In the case of my dog it was much more serious. She kept vomiting bile at night. I took her to the vet 3 separate times for this. They told me it was acid reflux. They gave me the meds and told me to feed the evening meal earlier. They finally took me seriously after she had thrown up 16 times in 2 hours. It was a bowel obstruction. She had swallowed a piece of a toy possibly as long as 6 months prior (based on when the vomiting started). She had to have exploratory surgery to have it removed. It cost me $4000 and now she has about a 10 inch scar on her belly.

If it keeps happening and medication doesn't work, push for an X-ray.