volume control problem

I have a new Sansa Express 1G with version 01.01.05A2 firmware (updated it the first day I got it) that occassionally goes to full volume when the + volume button is pressed just one time! Trying to lower the volume by pressing the - is ignored and it takes several second of repeated pushing the - button before finally responding to lower the volume. Since this is a new unit (only a few days old) is it a known hardware problem or is it a known software problem that can be fixed with a download? If it is a hardward failure, then I will need to get an RMA and exchange it from the retailer. A prompt reply to this query is greatly appreciated. Thank You!