Thanks everybody for the replies. Very interesting and the Arkel bag looks like a viable replacement if I decide to go that route. One question for the Arkel bag owners. Do you need to depress the snaps on both mounts to remove the bag? Looks like that might be a little awkward.

So I started today by calling Ortlieb. They seem to be aware of the problem and claim it is rare. They told me that when the snap fails it is usually the because the hole in the plastic frame is a little larger than ideal and that sometimes it is because the male rivet on the snap is too small. They asked me to return the bag and that they will inspect the bag and that if it is the hole in frame that is the problem they will replace the bag and that if it is the rivet they will repair it. Seems reasonable so I am going to return the bag and let them fix it and see what happens.

One very intersting thing I learned is that beginning in January 2013 they are offering a redesigned Ultimate 5 Plus bag that will use magnets instead of snaps and will have a small handle on the front of the lid so that the lid may be opened and closed in one step with one hand. So anyone thinking about buying one of these bags may want to wait until early next year.