I have waves, and after mentioning this to my flooring guy, he said they are at an acceptable level, meaning they are there, but not to the degree that would warrant a re -sand. I have to say that they are a little noticeable all the time, but very noticeable in certain lighting....I have heard different views on weather or not waves are just something that you just have to accept , or that they can be eliminated...
The floor I have is very dark, and I imagine this makes the problem even more apparent. Just wondering if this is normal, and can the wave be diminished later, by switching to a matte finish instead of the satin that is down currently

If he would have cut the floor on an angle for the first sanding pass then he would reduce the possibility of wave dramatically. Its a difficult thing to say weather it's acceptable or not, You're suppose to evaluate a floor from a standing position under normal lighting.