Is There Something Wrong With John McCain's Head?

No, I'm not questioning either McCain's intelligence or is sanity, but for the past several days, where McCain seems to be, he is wearing a Navy hat. Is he hiding something on the top of his head? Or am I just not seeing him without it? Just asking.

Update: And, of course, as soon as I post this, I see a picture of McCain and Bush 41, and McCain is hatless. He was wearing the hat at a campaign event in Maine a few minutes ago, and when I saw footage, I was inspired to post. Never mind.