Apparently taking a page from the MS W10 playbook... I just checked available storage on my iPhone 5/iOS 8.3 and looked at what was taking up how much. Much to my surprise, there's iOS 9, which I think was 903MB. I've had 2 or 3 prompts saying it was available, dismissed them, have never checked what the changes in iOS 9 are in Settings|General|Software update, nada. (Btw, doing the latter with past updates IIRC may have initiated a download) Deleted the download, but on the not cool at all list...