There are lots of questions regarding Android on SO even when there is an android SE site. So should I flag that questions to be migrated or just comment on question to tell OP to ask android on Android.SE next time or leave them as it is? Flagging questions can become a headache for moderators as they have to handle too much requests in this scenario because there are lots of android questions are being asked on SO.
Android.SE is for Android users, not for developers. Questions about development of Android applications should not be migrated!
From their FAQ
If you see a question about using Android that has nothing to do with programming, flag it for moderator attention.