I researched Black Bears online and feel much better. This site seems knowledgeable:
Here it describes my situation:
We have seen a lot of advice to avoid eye contact and avoid running away, but we have been unable to find any instance where doing these things has precipitated an attack. Fearful people usually tell us "I ran one way and the bear ran the other."
I'm going to buy a can of pepper spray and keep it down at the oasis just in case a bear becomes a nuisance. After reading that article, I realize the bear may not have been threatening me, but rather exhibiting nervousness. (My rapid departure probably decreased his nervousness dramatically.)
However, Wikipedia says that snorts are aggressive behavior, and further states, "Black bears rarely attack when confronted by humans, and usually limit themselves to making mock charges..."
At the time I felt like he mock charged me, which was probably a nervous reflex on his part.