SAN is the second-busiest single runway airport in the world! I'm not surprised that aircraft have to do a 'go-around' there more than other airports. Having it happen twice, while unusual, isn't unheard of. All it takes is the a/c ahead of you taking too long to exit onto a taxiway or a plane taking off to sit a bit too long before roll-out and you've got to do a missed approach.

http://en.wikipedia.org/wiki/San_Die...tional_Airport