I think it makes sense...you're not eating much of anything, so it will stand to reason that you won't go much. Hey, on the bright side, you could be running nonstop. Another post-Nissen member I just responded to is having that problem!
Are you still on narcotic meds? They slow things down. Try not to strain...just keep drinking, try to eat something, and things will start moving. If you get really worried about it, call your surgeon. I'm sure they get that question all the time.