This is happening on some phones when the weather is hot. We are working to resolve the problem. If this is happening to you, please post here with your device make and model, and your OS version. It may help us hunt down the problem.
Right now we know it happens on the DROID RAZR HD.
We believe this should be fixed now on the most recent update 1.4.5 - if you have version 1.4.5 and are still seeing this bug, please let us know.