I asked a question and I can see a reply in my inbox. If I click on the message it takes me to a reply on the the question I asked, but it doesn't appear to be the same answer as the precis I can see of the inbox message doesn't match the answer on the question page.
The only way such thing can happen as far as I can tell is the answer was edited during its grace period. There is 5 minutes grace period after each edit (or after initial time of posting) during which any further edit is not recorded as a revision but merged into the original revision.
The only way to confirm this is by asking the answer author in a comment, something like "Did you edit your answer shortly after posting it?".