Found that, sometimes my glance screen getting displayed upside down, interestingly sometimes mirrored view of the same and blinking of glance screen some other times. I'm using glance screen background. But seems that it's not the culprit. Read the similar issues at windowscentral.com. But, I'm not using remote desktop app.
I'm on Lumia 620 with Windows Phone 8.1 Update Developer Preview 8.10.14219.341, firmware of 3058.50000.1425.0001 and Glance Background 126.96.36.199