Good score! What brand? As you've probably discovered
selvedge means a finished edge of the denim, so an extensive amount of stitching at the edge isn't necessary, and it makes cuffs look great. To make selvedge denim, it requires an older style shuttle loom that isn't as fast as a modern day projectile loom. The textile mills creating selvedge pay closer attention to quality, because the lower output and higher cost demands it. Not to say you can't get good quality from modern... it's just not as desirable without that clean finished edge.
An interesting read about selvedge and why it's more than just the edge that is superior:
selvedge vs. raw denim.
Anyway, denim is a very dynamic textile. It will shrink and stretch, the degree of which by how its laundered and the fitment to body when worn. It's also very much dependent on the denim being raw versus Sanforized. Yet, even Sanforized denim can shrink if put in a machine dryer on medium to high. The main thing is, always launder in cold water and if you have to use a machine dryer, use the delicate/low setting, and remove when still somewhat damp (let it dry the rest of the way hanging). If the jeans are a bit too loose on you, you can force shrinkage to get a better fit--just do it gradually in steps until you get the fit you want.