Vikings fans should be concerned about Percy Harvin missing this weekend against the Bengals.

He has not practiced, even on a limited basis, all week. Migraine headaches are the reason given.

This is likely the problem that has plagued him since the offseason, when he was forced to cancel some pre-draft meetings and miss the Rookie Symposium, though I don't think that has been reported yet. When I asked Harvin about this back in September, he did not say if this was it.

Don't count him out for this weekend, given his toughness. But this is clearly a concern.