Vomit when excited?

[nitinleew]

My 4 year old poodle eats in the morning at 6 am and not again until 6 pm in the evening. When I come home from work he gets very excited and sometimes will spit up what looks to be a little bile -- frothy and white, though sometimes it's the color of his food. He does this maybe once a quarter. Anyone else have this occur?

Thanks.