Others have had the issue, but it isn't a wide spread issue. The other thing, since you have extra phones, this is what I would do.
Send back the warranty phone, call Samsung, send them the phone or phones, having the issue. The will remove the software, which is better than a reflash and then install the software back. They will also check everything in your phone, top to bottom.
Many times removing the software instead of reflashing, fixes it. Also if you have a bad motherboard or something like that, they will correct it.
I 100% would do that with having an extra phone to use while they have my phone, not get a warranty replacement that is a refurb or used phone.