The current excuse around here is that refineries are switching over to the "more expensive 'summer blend'". If I recall that was the reason for a spike last fall, when they switch over to "more expensive 'winter' blend".
Supply continues to outpace demand, say the reports, but crude prices are creeping upward which may sort of backfire. As prices top $40/ barrel it becomes more favorable for the domestic producers to get back/stay in the market perhaps.
Personally, I think they should buy all the foreign oil they can for as long as they can and save the domestic reserves for the future. Never happen when there is money to be made.