Stripes on picture windows

My six new 4x6 picture windows have stripes on them in the low light of dawn and dusk. Four of the windows have vertical stripes and two of them have horizontal stripes. The stripes are about 2 inches wide. What are these?It is insulated glass and the stripes are inside.

I have read and I agree to glassonweb.com's Terms of Use, including Privacy Policy and Cookie Use.
On