Judging color from negative scans can be tricky, since most scanning software tries to set the color automatically in one way or another. If these are shots of airplanes in flight, as you seem to suggest, getting the color right will be particularly tricky, since the software may try to bring the overall color to a neutral gray. With an overall (correct) blue color because of the sky, the result will be off, probably with an overall yellow cast. I've seen all sorts of sky colors in scans of sky-dominated shots -- green, yellow, orange, etc.
Thus, based on what you've said, I'd say there's insufficient evidence of color shift in your negatives. I can't promise that the color hasn't shifted, but I wouldn't conclude that it definitely has shifted, either. If the color has shifted, many scanning programs include an option to correct for color shifts caused by age, if you want to get good scans -- but you'll also need to deal with the blue-dominated images, if that's what you've got, in some other way. For optical (wet darkroom) printing, I'm not sure what guidelines to suggest for adjustments, but of course you'll probably have to create a custom filtration setting anyhow, so I'd just approach it like any other unknown negative -- do a color ringaround, etc.
