I would say virus as well.
I remember freaking out one night during the Superbowl, when my DD had a fever of 103.7. It was nighttime, so the doctor's office wasn't open. I called the nurse's hotline and they reassured me that as long as she wasn't ACTING sick (lethargic, throwing up, super grouchy...) that it was most likely a virus...
It was funny, because spent most of that night dancing to the superbowl commercials. In the morning, she was still a little warm, and by that afternoon it was completely gone.
The fever is a GOOD thing! It means that her immune system has kicked on to keep her from getting sick... not necessarily that she is sick. :)