Did Al see this sign on his way to college in San Luis Obispo, causing him to use the number 27 in future songs, videos, and interviews??

It's a nice theory, but probably not true. This sign is on the southbound lanes, north of San Luis Obispo. Al drove northbound from his L.A. area home, south of S.L.O., and couldn't have seen the sign without going way out of his way!