Google license check suddenly fails on development device

I released an app that uses Google LVL in the market many months ago. For some reason, an instance of the app on my Nexus One mobile phone consistently fails validation, starting about 3 days ago (March 25, 2012). Clients using the same version of my app don't report any crashes. I tried to switch the answer to licensing via developer console - license check still failed. I have uninstalled and reinstalled the application so as not to be affected. (I install the app on my developer phone using adb as Google won't let me buy my app through the Store). I'm wondering if this issue is related to recent changes to the Market / Play app. the phone runs version 3.5.15 of the Play Store. Does anyone know why this might be happening,and how to fix it? Thanks, Tom