Anyone else experienced the following?

I had an itinerary booked for travel in September, so its a way out. I booked it sucessfully using the flight numbers which were in play at the time. Well now, DL has updated their systems and some flights have slightly different departure times, or have changed flight number.

The problem is, when I go into "My Itineraries" on DL.com, it only shows me the seat layout for the unchanged flights - the new flights which I am now booked on do not show a map (or even come up as a choice). There appears no way to choose a seat for a flight after DL's schedule changes.

Do I have to call SMS/DL or is this a glitch in the website whenever DL changes its schedule?