Yeah, GVs often think they are "hidden" because some of their own views are blocked.
Here's OPs view from film showing how little of Maine's wirb was "concealed" by the bush in an open field. Wirb Driver and hull gunner views would be obscured, and the turret would feel surrounded by the bush, but it's still above the bush height.
Maine firing is what gave OP the location.
The bush(es) wasn't big enough to show until zooming closer in, so Maine's wirb stood out as a teensy speck in an otherwise open field.
Here are some screencaps of OPs film and views. I have trails on in film to better highlight the wirb.
First potential view.
Shooting doesn't help hiding.
The wirb has no clothes!
There you are!
In! In! INNN! Notice the lack of bushes from that distance?
Dead shortly after.