I totally agree with Prism99. There really doesn't look to be much difference, and a 3 yr old won't notice - or care - anyway. Keep going with it, and put it down to a lesson learned with cutting with rulers.
Don't forget to show us the finished product.
This would be my recommendation as well. There is absolutely NO need to re-do all of that work! Ease those longer strips in and you'll be fine.