Further research uncovered the folllowing:
These are 'easy install' valves that are supposed to last 10 years. They don't prevent damage in case of a hose failure. So if yours won't stay in (on) you could use duct tape until the plumber arrives.
I called the warranty department who gave me the name of the plumber who did the work. They told me the valves weren't under warranty (after 7 years) but they would replace at $70/hr for service and $15 per valve.
The link below will give you some more perspective:
http://www.terrylove.com/forums/show...ow-tite-valves