It could just be some random virus that only shows itself as a fever. 103 isn't that high in a little kid. Personally, I would not give tylenol unless my dd was uncomfortable and I felt she needed it for comfort. I would watch for other signs, most importantly, behavioral signs. If your child is not listless, etc, I would just keep watch. Also, encourage fluids, as a fever will dehydrate.
Most likely, it's nothing big. Hope your dc feels better soon!