Ingrid...no, I don't think my tension is on the tight side.
Conti...yes, that is what I mean...the alternate squares are "poking out" and "pushing in". Perhaps I did not explain myself well enough. Of course I knew it wouldn't be a perfectly flat blanket, but it looked too wavy to me. However, I just now laid it out on my bed, squishing the end stitches (since my circs are a bit shorter than the blanket) and smoothing out the middle. I think it will be okay after all. It looks better the more rows I knit. The waviest part is the edge, which as you said, Ingrid, will be taken care of by knitting the garter ruffled border.
Needless worrying, I suppose, but I hate spending hours and hours on something that isn't going to come out right.