If it only happened once, I wouldn't be too concerned. If he does it again, here is an excellent article on how to deal with it (commonly known as object guarding):
http://www.clickersolutions.com/arti...ctguarding.htm
Joey had issues with this as a puppy, but thankfully we've worked through it using the methods described in the article.
This particular behavior really isn't about dominance; it's about being afraid that you are going to steal his food. Understandably, it's a common behavior, especially in the wild.