I saw them yesterday mostly as light grey clouds. But at one moment, those clouds turned slightly red to me. I am at a very bright location and quite far to the

I saw them yesterday mostly as light grey clouds. But at one moment, those clouds turned slightly red to me. I am at a very bright location and quite far to the south. So I only can assume, that their brightness was at the brink of color vision and that my eye wasn't perfectly adapted to the dark. In better circumstances and perhaps with a tiny bit more "signal", they should appear in colors.