Weird tiny birght square in viewfinder

I noticed recently on my a70 when I use the viewfinder just to the left of the bottom cross hair there is a shiney blue square. It isn't there when the camera is off. The picture on the LCD is fine and so are the pictures when I put them on my pc. Any help..please

Also, if I zoom in the bright square goes away, but comes back into the view finder at wide angle mode.

Sounds like a reflection in the viewfinder lens. You just have to find out what is reflecting.
Anyway, if it isn't effecting your images, why bother about it. I for instance never use the viewfinder, only the LCD.

Martin