Really funny you mention that! I’ve been using it for several months without any issue at all in both training and racing, but this past weekend, I did Ironman Arizona and near the end of the first lap over a bit of a bumpy section, my bottle popped right out during the race. Had to quickly stop and go back and pick it up. Took a bit of time, but I was able to get back with the group I was working with. Next time, I will either tape or use rubber bands to keep that thing in!
Sounds like drafting to me.