Thats really funny. I used computer analysis for few games, fortunately so far I never came across this.
Let me put the thoughts this way, if the computer analyzes the position for 'N' moves. The computer analyzes N moves including Bc6 and finds Bc6 is bad because of e5. After the move is actually made, the computer analyzes N moves excluding Bc6 and finds Nd4 is better than e5.
It is normal to see a position where computer changes its stand in one move (or half-move?) But degrading a move (e5) from best to inaccuracy is really very very rare.
Specifically on Move 12, the analysis shows my opponent makes a a mistake, and then gives 2 lines - the mistake line, and the better move line. In both variations whites best response (according to computer analysis) is 13. e5
However, I actually did play 13. e5 and it gave it as an inaccuracy...and says Nd4 is better. Which is the better move for white?