I get the point about aesthetic design if the entire bike was like that but only the top tube seems out of place, hence my query. The bike is in a well lit room with roof windows where I prepped it for ride wrap, so when the sunlight hit it, I noticed, as you would when riding on a good day. The torch was only used to check over the frame for scratches defects etc, so not OCD by any means, but over here when you pay $13k for this bike I think its fair to check it over in detail.
The strip you mention, I agree in the sense that it doesn't look like a good bit of aesthetic design, whatever it is... Indoors you can't see it, but depends on the light intensity.