Should I return my XT20

[dubiouswatermelon]

I recently got an XT20 with the 18-55 kit lens. Today I was trying it out at home, when I found out that when I try to zoom quickly in or out in manual mode, I see a horizontal light appear for a fraction of a second on the EVF. I cannot see this happening on the LCD. This happens only in manual mode, and not auto. This does not happen when recording a video. I am using mechanical shutter. But I don't think this is a shutter issue as I see this white line for a second when zooming quickly. Also I don't see it when I see EVF auto brightness from Auto to manual. The firmware is updated. Also tried zooming outside, I don't see that issue.

The issue is as described here by another user: