Yeah my tank is always around 28 degrees, pretty sure they don't have whitespot. They've been doing this for months... I figured it was probably about time that I tried to figure out why... is there any chance that it is just because they are itchy or something? I mean we scratch too and there isn't necessarily anything wrong with us to cause us to do so.
They really have no visible signs of disease or damage. Other than that behaviour and everything else is fine, they eat, look colourful etc. Maybe I should just continue to ignore it...