that's a great quilt! I really like the pattern -- I'm thinking it would looks great as an all-over scrappy. And that panto is the perfect choice.
I say don't fret about the tension, since the top looks good. It will adjust a little bit once it's laundered. Just chalk it up to learning for the next time. I try to do sample stitching and look at both the top and the bottom when I'm starting to longarm a quilt.