It also could be that they just had (or were fidden' to) turn the airport around. (i.e. switch the direction of the runways). This is very common when wind directions change.

Additionally, the other planes could have been waiting to turn it around because their TO performance wasn't as good as the DL flight. It's not unusual to hear pilots turn down a RWY because of a small tailwind due to TO performance.

They also could have been sitting for MIT (Miles in Trail) delays. Not familiar with SNA, but they may not have a hold pad at the end of the RWY you used.