Happens with the Estimote app and SDK:
10-30 13:22:13.769 20203-20203/com.crowdcompass.eventshortname E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.crowdcompass.eventshortname, PID: 20203
java.lang.IllegalArgumentException: This cannot be run on UI thread, starting BLE scan can be expensive
at com.estimote.sdk.internal.Preconditions.checkArgument(Preconditions.java:65)
at com.estimote.sdk.service.BeaconService.checkNotOnUiThread(BeaconService.java:529)
at com.estimote.sdk.service.BeaconService.access$600(BeaconService.java:62)
at com.estimote.sdk.service.BeaconService$InternalLeScanCallback.onLeScan(BeaconService.java:517)
at android.bluetooth.BluetoothAdapter$2.onScanResult(BluetoothAdapter.java:1703)
at android.bluetooth.le.BluetoothLeScanner$BleScanCallbackWrapper$1.run(BluetoothLeScanner.java:330)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)