What would it mean if i got a fever of 100.0 the day after i got a hida scan for gall bladder but it went away in a few hours?

Probably nothing: Particularly if the fever resolved and you have no further symptoms. You may have had a minor reaction to the dye, or other aspects of the procedure. Suspect you are going to be fine, as long as your gall-bladder is doing well. Hope you don't need surgery.

Probably unrelated: If hida scan was normal the fever may be unrelated. An elevated temperature suggestive of infection is seen in 1/3 of patients with cholecystitis (inflammation of gallbladder and > 90% with cholangitis, inflammation in bile ducts. These patients usually have abnormal results to the gall bladder study.