oven spring

So, before I ask my question, I must crow just a little.  I finally 'got' how to knead dough in my DLX.  I have successfully produced about 10 loaves of wonderfully soft and fluffy sandwich loaves of bread that my children will finally eat without being held down and forced into there tiny little mouths.  Go me!

Anyways, never before in the past, when using any combination of dough/recipe/mixer did I acheive a decent oven spring.  I always got some decent rise at first, but when a punched the dough down and put into my pans, rarely did I get a double rise.  It didn't matter how long I allowed the dough to rise, it never doubled.  And when I would bake it, it would just stay at the same height from when I put it into my oven. 

So after watching about 4 hours of classes from the Bread Beckers, I used their basic recipe, using all purpose flour since it was all I had available to me (I was camping in my RV).  I used just a smidge less flour than the recipe called for, did not do a first rise, just allowed to rest for 10 minutes, shaped, let rise for one hour, and baked. 

And FINALLY, when I took the pans out of my oven, had bread that had crested the top of my loaf pans!!!  And the texture, was so soft, so enjoyable.  There was no choking or gagging on dry bread.  Even the next day (that's as long as it lasted, I'm happy so say) it's texture was nearly the same.

I've since repeated the above with a few different types of flours, and it's worked ever time.  So here's the question: Why do I suddenly have oven rise, after  8 years of stumpy loaves of bread?  Is the answer simply that I've been using too much flour? 

Any insight would be fantastic!