Black (LC?) seepage inside watch, ruining display

My husband's watch screen has failed twice with the same problem. A black area approx. 1/4" appears in the top RH corner, and then a day later the entire watch screen goes red. The first time we took it to the Apple Store, they told us he must have hit it on something and caused the liquid crystal to seep into the screen. We dutifully forked out the $400+ for repairs. But now that it's happened a second time in exactly the same place and exactly the same shape, I'm wondering whether it is something else.