I firmly believe that pregnant women don't waddle because of their funny shape, but because of the resulting back and hip pain/tightness. That's why stretching helped you walk more normally; it relieved some of that!
I find that I don't waddle when I keep up with my yoga, and I waddle when I don't. A few minutes of stretching (and sometimes some tylenol, depending on how bad the pain is) helps me knock it off when I notice I'm being a momma duck.
Yes! I had the very same epiphany a few weeks ago. I always thought pregnant women waddled because of their big belly's but nope! It's the sore back - and altered center of gravity, I'm convinced. I always waddle less when I get my morning lap swim in, it loosens me up!
Also, my DH callis it my "Pregnant Lady Swagger"...bless him! (He also says I'm lovely when I shudder at my double chin or pitifully try to stretch a non-maternity shirt down over my belly )