Possible late night highway sighting on I-10 near Sonora

The witness was driving east on I-10 near Sonora around 1 a.m. when headlights revealed a tall dark figure standing in the center median. The figure rotated to keep its side toward the vehicle, then turned to face it before running south across the road with a forward lean and pumping arms. The witness turned back and searched the median for about 30 minutes but found only grass and no tree or bush to explain the figure.