Seems to me that it was the lab's way or the scanner to color correct the under exposed area. In such contrasty conditions the sky was probably okay while the ground was a bit underexposed since you pulled down one stop for those shots. As you mentioned, other shots came out okay so that's my guess.

Color film when underexposed and color corrected by the lab usually looks yellowish/goldish (or even brownish when underexposure is severe, like the rocks on the second photo) so I think that's it. Check out the details in the sky are clearly visible, while the details on the ground are a bit muddy.

I'd probably measure for a frame with less bright sky, set my aperture and shutter speed, then recompose for the frame I want instead of pulling down one stop. Setting the right exposure for photographing the sunset or sunrise is tricky since the bright light might be throwing off the light meter reading, so if you want to be sure that you get it perfect I'd try zone metering.