If there was any question as to whether Monday’s Merriweather Pavilion concert was a double bill or a straight up Shins show it was answered with the first spacy sounds of the Portland-based band’s set-opening song “Sleeping Lessons.” When the lights came up, so did the happy hands of the Shins fans that had staked out the front of the stage, finally loosing the screams they had patiently swallowed while Austin-rockers Spoon buzzed through their mid-show set.