Twice in the past week I have had a high fever. No obvious signs of infection. No other symptoms. The temp was around 103.?

Get checked. A low-grade fever (99-100) without other symptoms is no big deal and can be ignored, but if you're really getting fevers as high as 103, this is pretty unusual and really should get checked out by a doctor soon (this week). Could be some sort of unusual infection, blood disorder, medication reaction or other underlying problem.