It seems it’s relatively common; I know at least another person who said had this problem, and so did someone I was in party with the other day.
I remember something like this years ago with flying mounts because they would not restore your mount or flight form buff when exiting an instance.
Another time I was traveling by Zeppelin when it changed areas and everybody onboard appeared in the air above Alterac Mountains. Needless to say nearly everybody died and low levels had a hard time getting somewhere safe 