Fail to reproduce results in a published paper. Is this an academic misconduct?
Academic misconduct is the last thing you have to consider, not the first.

First, you have to consider that there might be something you are overlooking (e.g. an updated version of the code, or the data set is not really the same, or something related to the machine or etc.). Then, you have to consider that mistakes happen, and as I wrote in this answer, yes, there are plenty of errors out there, that do not come from academic misconduct: a mistake can have leaked somewhere in the paper, code or graphs.

Therefore, if you have reasons to consider that difference significant, you can contact politely the authors trying to set up a scientific discussion -- not an accusation -- to understand where the difference comes from.