I've seen the same thing Lesso described, where the plant is like, "Hey this season/grow spot is extra good", foxtails are a survival mechanism that takes advantage of what the plant percieves as a good microclimate or longer breeding season, combined with a sense that it hasn't been pollinated yet and is hoping for some pollen, even if it has to make its own, and yes bananas are often part of that equation.
I've even seen it indoors on some strains (I recall my Pure Power Plants doing it) , and will set the foxtail bits aside when manicuring and dry them separately since they are not going to have time to fully ripen. They're great to use for cooking.