I don't tumble dry my jeans, but on low I assume they will stretch back. I line dry mine and the waist does stretch back. Sounds like this might be your first pair of unsanforized... remember tumble drying will shrink all of the dimensions, but not everything stretches back like the waist does. But really, we are talking quarters of inches here, so don't lose sleep over it!
A "long" time ago (2011?) I was in dad-jean mode and picked up a pair of washed, non-selvage Todd Shelton jeans due to the long inseam option. Customer service was great and the fit was just what I needed. I discarded them when I blew out the crotch -- shame I didn't know about darning back then.