Was it date entries as a tourist?I don't believe they verify your NPR dates before even getting to the AOR.
I had some error in date entries which impacts physical presence. It didn't impact in my case since I applied 3 years of presence in Canada post PR status. Didn't even consider my NPR time in Canada.
Because they track your entries and exits anyway, but what they also care for NPR time is if you had a valid status, and for a tourist status, it is not always available in their system, especially when you are from a visa-exempt country and they don't issue any document (while other status like student or worker are always registered in the GCMS, when they are issued).