Last February, Band of Horses frontman Ben Bridwell performed an incognito solo set at 52.5 Records as part of the store’s birthday celebration and food drive (he was booked as mystery band Birdsmell). Then Charleston-based Band of Horses finished a busy 2009 with a last-minute booking of an off-night holiday gig at the Music Farm (Mon. Dec. 28). Bridwell and his bandmates — drummer Creighton Barrett, bassist Bill Reynolds, keyboardist Ryan Monroe, and guest violinist Laura Cortese — filled the Farm to capacity with rabid fans. It must be nice to be able to charm the local scene with such a casual, spur-of-the-moment gesture.