I agree with Bucky, it is probably a sending unit problem. How are you monitoring the temp? I use a Scan GuageII to monitor mine and it seems to run warmer than monitoring through the pan like my previous truck. I would go ahead and change the fluid and just keep an eye on it.
Just got my 2003 7.3L F350 back from getting new injectors installed yesterday. Ran great on the way home. Good luck, I think you will be fine.
As far as changing the fluid, I just changed mine a couple of months ago following:
hereIf you go to Guzzle's page and look around, he has a good how to on changing the transmission fluid.
