Hey, this is the phone communicating with the network operator to get necessary info for the SIM. Most devices do this in background so you don't have to bother but Flyme shows a draw over screen pop up until the phone stops getting/sending data from/to the network operator. It is completely normal and there's nothing to worry about. This happens on A firmware too.

I reseaves that too when i was using G,
Intreating,
Some one know what is this?
Rudra?

can u post the picture of ur phone too? i mean when the problem occured.