Just a thought until there is a preflight panel - in terms of tracking down the culprit text-frames, if you do 'view > zoom > zoom to document' - no matter how many pages you have, you will zoom out to see thumbnails of all pages at once - the little red alert dots do NOT scale down with the thumbnail, so it's really easy to spy which page(s) have overflowing text (assuming as above, that you have 'show text flow' enabled and are not in preview mode)
