If there is no reason to question or doubt that you are in compliance with the PR Residency Obligation, there is no reason to worry about that.
If there are only minor discrepancies between what you represented as dates of your stays in Canada and what CBSA and other records indicate, that too should NOT be anything to worry about.
It is possible that in the course of the PoE examination (should not be a "grilling") the PoE officers were testing your answers. That, in itself, should be no cause for concern. That is part of their job description. Like police. They are, in fact, in effect, border police. It's their job to ask questions before allowing travelers to enter Canada. And especially so when travelers do not present valid travel documents demonstrating authority to enter Canada. No big deal, NO PROBLEM . . . so long as, of course, the PR is in compliance with the Residency Obligation and answering questions truthfully.
In contrast, obviously, if you are short of being in compliance with the PR Residency Obligation, you were lucky to not be issued a 44(1) Report for Inadmissibility.
Just as obvious, if any of the answers you gave the PoE officers differ from the truth significantly, that would constitute misrepresentation and potentially a separate basis for deeming a PR inadmissible.
So a lot depends on the particular situation, on your actual history, whether you have cut-it-close in complying with the Residency Obligation, how truthful your responses to questions were, and so on. Including how well you have settled in Canada, and whether or not it appears you have, consistent with the grant of PR status, PERMANENTLY established your life in Canada.