This started happening about a week or 2 ago. It's most likely on the MapQuest end. I was thinking it was a "temporary outage" on their part, but I'm now beginning to think the free ride for snagging maps may be over.. lol. I'd love to see a remedy. Luckily i only had 6 instances of the module, so I just saved the maps and used the text/html module to create static versions w/ links to the mapquest url.
David Murray
Ikaika Web Solutions
http://www.iwebsolutions.net