Help, O Humble Ripplers

This is my first crochet project and I learned the stitches from the videos at www.nexstitch.com. I'm practicing swatches using the Soft Waves pattern, but my swatches keep coming out curved. At first I thought it was cause I was using too small of a hook. The top two were done with worsted weight yarn and 4.0mm hook. I then switched to a H8/5.0mm hook for the third swatch, and then to a I9/5.5mm for the bottom swatch. Now, I'm thinking the curve must not just be my gauge, but something else. Is this normal- will it straighten out as I go along? Have any of you had this?

ripple hints

Ok, so I am finally on the right track with my ripple blanket. I had to start over twice due to problems at the edges of my blanket. I didn't end my rows at the correct place in the ripple so I was ending up with too many stitches on one side and not enough on the other side. In case anyone else is having the same problems starting out, I wanted to refer you to some great advice I got on the Livejournal CrochetCrochet community. The not-so-mathematical chain stitch start (chain more than you need and then just rip some of the chains out when you get to the point where you want to end your first row) worked so much better for me than trying to count out 200-something chain stitches. Maybe I'm just not good at counting, but I thought the advice might be helpful in case anyone else is experiencing the same thing. Also, drawing a diagram of the last ripple helped me see where I would increase and decrease to keep the number of stitches the same.
http://community.livejournal.com/crochetcrochet/237901.html

~amanda