I'll vote for over-thinking it. Your bonking may simply have been acclimation, a little energy boost a few more miles and you probably would have felt fine. My minor bonk points are typically 35 and 80 miles biking, 10 miles running. I come to just accept it and work through it. Next time it happens have a snack, ride through it, and see if you come out the other side. Do hydrate, becoming seriously behind the curve hydration-wise is miserable and tough on the body.