It's not uncommon for a baggage cart to be carrying bags before and after visiting an aircraft, especially when they are bags that are being transferred to/from other flights. The originating bags are typically delivered first (those carts usually depart empty), followed by transfer bags. On one flight recently from Dallas-Ft. Worth, at least 4 different transfer carts stopped at our aircraft in the 15 minutes that we were sitting on the plane before departure, and each of them still had bags when it left. Of course, GSX is trying to represent all bag loading/unloading activities with just one or two carts making a single visit for each operation.