I'm probably in the same boat here when I eventually get to that point in the process. My only trip during my 4 year period is from August of 2011 (to the US - for my father's memorial) and when I came back to Canada (land crossing) they just scanned my passport and PR card and waved me through - and no stamps. Even though I have not traveled anywhere since then, I am sure a CO will not have any compassion or discretion over this CBSA oversight.