Oh yes, I know that's exactly the sort of thing that would happen to me, so don't worry, I'd just finished cleaning it in that shot, and it's now already wrapped, boxed and well out of the way on a high shelf
I get a touch paranoid with such things, having once spent hours carefully grinding a 10" x 8" glass focusing screen I'd made for a camera I was building, left it on the work bench for just a minute, while I rummaged for some 1/2" screws, and one tiny screw tumbled off the shelf and landed perfectly, point first on the glass, shattering it to pieces. At least in that instance, I just had to cut another piece and start over, but, as soon as I saw that dial glass, I thought that's something I really don't want to be breaking, as I imagine they're pretty rare to come by and it's in fairly good condition. The radio was in a cold, damp loft for a long time, so it's got a few small areas where the black paint is missing, but fortunately nothing much encroaching on the lettering or details, so I presume a careful dab of black paint here and there with a fine brush should make it look presentable?