I had the same issue on my '05. As the others pointed out, it's more than likely a low voltage issue. A new battery cured mine.
Forgive me if this is obvious, but a full overnight charge before using is a good way to start a new battery out. (NAPA sells a dandy shipped dry / add acid bike battery that's a slight bother, but at least you know it's fresh that way.)
Of interest may be the fact that at 11,000 miles, the high amperage contacts on my starter relay were snug, yet in dire need of a proper cleaning. I took it as a cue to clean all the starter and charging contacts with a little wire brush. It only takes an hour or so. I do believe I'll make the wire brush deal part of the Spring tune up. I hates walking home.
