I ran from Fountainhead over the weekend and noticed the trail has changed/been re-routed. The one mile marker is clearly much longer than one mile from the mile zero marker. Anybody know anything about the change and why that first mile is so off?

It was due to trail and forest damage. The 1 mile marker is at 1.6994mi (wheeled), and the 2mi marker is exactly a mile between the first mile marker.

I think the trails were re-routed due to storm damage / erosion, but that's just a hunch (having been there recently myself), I don't have any actual details.

The reroute was done in collaboration with the park and the Mid-Atlantic Off Road Enthusiasts (MORE) mountain bike club as the trails have been opened recently to MTB use. The trails were in poor condition and the collaboration allowed/assisted in the reroutes/improvements.