It's funny, we had a similar experience both ways down to VA. On the trip down I plugged into the HPWC until a spot opened, but on the way back there was a red car and another car there. We parked next to one of the cars and waited for a spot to open. As the spot was opening a woman with DC plates drove up and tried to go in (even with my wife standing in the spot so that I could maneuver in). She let us park, and we went into the mall.
We were there for about 35-40 mins and when we came back out the same red car was still there charging, the poor woman with DC plates was still waiting, and there was another guy there along with another car pulling in. A rep from the Tesla store was out as well, I guess looking into the red car and why it had been there so long. In the future I'm just going to continue on to woodbridge on the way down, and perhaps charge in WB on the way back up (which will be cutting it close, but less stress).
Tesla should make this location permanent and expand it if they can. It would also be great to have notification/queuing for SCs