7D mk2 sensor astro long exposure problem

[NNature]

I have recently noticed that if I take longer exposures than 1 minute I get a couple of wide horisontal lines in the images. I haven't noticed that before. One green-ish horisontal line 1/3 down from the top and one magenta-ish 1/3 up from bottom.
This image is a stack of a bunch 2 minute exposures and brightened up to show the lines.
https://www.dropbox.com/s/jc785p13o6oviod/20161005_MG_3289-bode-100mm-120s-iso800_Edit.jpg?dl=0

The stacking is not the problem. You can see it on this single 4 minute exposure that the lines are visible. This is also over edited to more clearly show the lines.
https://www.dropbox.com/s/cbw7s4qpdwmal3g/20161004_MG_3218.jpg?dl=0

Should I be worried or?

 

[NancyP]

Do the lines show with 1 min or less exposure?

 

[NNature]

No they don't show up with 1 minute exposures, not even stacked.

 

[bluemoon]

try jpg and raw to see if it's in both. If it is, then try different processing software. If it shows up in both again, at least you eliminated some other possibilities.

pierre

 

[NNature]

I just tested it and it's both jpg and RAW that have the problem. The lines are visible in both Lightroom and DPP and even in the camera. I actually even saw it in the 1 minute exposure this time. I photographed the roof indoors with ISO 100 and f32.
Hmm... I have no idea what it can be...