Fabrication, Falsification, and Plagiarism

Description of the Problem

You are a co-author on a recent paper that was rejected. The referee made a couple of good points that called into question a section of the paper. The lead author, a fellow graduate student, is responsible for rewriting this section of the paper.

When you read the new version, you see that he has changed some of the numbers to address the referee comments. His response to the referee is that upon double-checking the data, there was indeed a mistake, and the referee was correct in noticing something was amiss. 

This student hopes to graduate within the next year, and you are aware that he is desperate to publish something before starting a job search. You are skeptical of your lab-mate’s explanation for the error, but don’t have any specific knowledge of wrongdoing.

Question

What should you do?

Fabrication, Falsification, and Plagiarism Discussion

Alternative Problem

A PI, who is desperate to publish in order to secure a grant renewal, has just been told by his junior student of concerns about the above paper. How might or should a PI in this situation respond to this concern?