yeahh i work in a drug store and this happens to me all the time lol
It's more like when you start talking to someone and you expect them to open with "How are you" and instead they start with "Hello" so you (anticipating the 'How are you') automatically say "Good, thanks"
This happens a lot in stores when you're checking out.
and both people just smile awkwardly and pretend it didn't happen
The person saying "Hello" is talking to a person who doesn't give a care in a world to what he is saying. At least, that's my take on it
This happens to me more through texting. It's not awkward as long as you go with it and the person who said "Good thanks!" doesn't realize that they screwed up, hahaha.