I am trying to check in for tomorrow's flight to Fort Lauderdale (postexam relaxation); however, nwa.com don't allow me to check in online by telling me that there might be a schedule change after the E-ticket was issued. As I can remember, there is no change to the schedule or flights. The ticket was booked on nwa.com about one month ago using a PD800; the last segment was operated by CO (EWR-FLL), the first two segments are operated by NW (BWI-MSP-EWR).

Is it because this is a WEIRD itinerary or some other issues? I hope I would not get the dreadful "SSSS" on my boarding pass tomorrow.