That was my fate yesterday as I collected my YYZ-EWR boarding pass at FRA (unable to get that final segment on either OLCI which I was able to do on LH's site as I had an inbound connecting MAD-FRA flight on that carrier. I prepared for the worst as I arrived extra early for my flight (delayed FRA-YYZ last night meant I missed original EWR flight and was rebooked for this morning), paperwork assembled, bag repacked for easy inspection. Though there were a dozen souls sitting in the waiting area of the Seconday room at T1, the agent doing initial doc review sent me directly to a customs officer who began the process.

Actually quite painless once I explained why I was flying into EWR this morning and flying back this afternoon.

Still not sure what triggered this but it is my second for the Americans who seem to spot check every year or so. Haven't yet had a Secondary using NEXUS or an agent entering Canada...though this afternoon could be a first!