The warnings indicate that the AndroidQuery library depends on the OAuth library. Apparently, you're using the former library in your project, but the latter library is missing. You could add the missing library, but if your application is working fine without it in debug mode, you can just tell ProGuard to ignore the missing dependency. In this case:
-dontwarn com.androidquery.auth.**
or, to the same effect:
-dontwarn oauth.signpost.**
See the ProGuard manual > Troubleshooting > Warning: can't find referenced class
(I am the developer of ProGuard)