No, he didn't make an alternative life style choice while in San Francisco. The truth is some cute girls at a pool party decided to paint his nails. And he is a good sport. And they were cute. (And I'm sure highly chaperoned, thanks to the band teacher.)
He says he had a good time, even though the band only got a bronze. Besides performing, they went to Pier 39, the Hard Rock Cafe, and Great America.
This wasn't nearly as surprising as when he returned from Mexico in 8th grade (2004) with his hair like this: