Only thing that can happen is that some dust can get into the cell and the acid with splash out and start eating things. It shouldn't hurt the battery though. My 1930 Chevy was driven about 500 miles with the 6 volt battery strapped in place UNDER the car where everything under the sun gets tossed at it from the road. I thought I would check the water level in the battery and found that one cell cap was knocked off - probably from a stone hitting it real hard and was missing. That was 2 years ago. Put a new cap on it and the battery is still good. - in other words - don't sweat it. If you don't have a digital multimeter - get one - they are cheap and indispensable for checking for open wires, shorts etc etc. Once you get one you will wonder how you lived without it.!!
Morris