Not sure if this is the appropriate place to post this but hopefully it helps someone.
After over 3 years of daily commuting with just my Nexus card (no passport) I get in serious trouble. Apparently, there is a recent update (no one informed me, nor is it on their website) that TN holders can no longer have their TN status tied to their Nexus card and as such MUST have their passport on them always as the officer reserves the right to ask for it. This is new and there is no were online (to the best of my knowledge to support this). However, it happened to me today and they actually proceeded to "disconnect" my Nexus from my TN and issued a replacement TN tied to my passport only (Same information as the last one just tied to passport only). They told me the update is ONLY for TN holders, non TN holders can use their Nexus card only.
I don't totally understand the reason nor do I agree with it but sharing my experience as it may help someone.