Looks that way. Wouldn't be the first time. I've lost a few bidons in my time over bumpy surfaces. Current score is 'Lostonbumps United: 8. Droppedwhiletryingtoputbackinbottlecage Town: 1'.
Maybe they should make King Cages bottle cages mandatory in the peloton on safety grounds?
Apparently a speedbump knocked them out