The answer!

Okay, no one posted an answer so I looked it up myself. The sun DOES set later at altitude. It also rises later at altitude.

At most latitudes on the Earth, the effect of increased altitude is the same: it makes the Sun rise earlier and set later than it would at that same location from the ground. The variation with altitude is approximately linear, and so we conclude that sunset is later by 1 minute for every 1.5 kilometers in altitude, and that sunrise is earlier by the same amount.

I am at 5,280 ft but the trail run I do is at about 7800 ft, or about 2.5 kilometers high. That means the sun sets about 2 minutes LATER than it would if I were standing in the same spot, without the mountain below me.

Cool. We just have to keep going up and the sun will never set? :)