Sounds like she's dropping them off of her brooding tracts, the breast areas hens use to brood eggs.
Doesn't mean she will go broody, just that hormonally her body 'thinks' it's soon to be time for brooding; however she may have other ideas. (She may not have the strongest instincts so may never go broody no matter how often her body prepares for it).
She may or may not go into full moult at the same time and drop all her feathers, hopefully not in one go but one by one.
Going broody has nothing to do with the eggs being fertile, or the hen having ever seen a rooster let alone mated with one. It's just a seasonal process that persists in hens it hasn't been bred out of (and even occurs in some that humans did try to breed it out of). Just like hens lay eggs regardless of whether they've ever mated with a rooster. It's got nothing to do with males.