It’s not the first line, but it is the first z move for that contour. It does seem to happen in 2 different “same spots” consistently, both at the z-move point on a contour.
G-code:
angso.nc (1.5 MB)
Generating gcode is new to me, so it would not surprise me to find that I have missed something. I already see many optimizations I want to make on this file.