Calling all knitters!! Out shopping today I found a (machine) knit scarf but didn’t recognize the stitch. It looked like stockinette with a thick-n-thin yarn… except when stretched. Can anyone identify this stitch? Sorry for the crappy cell phone photos.

stitch_front1 stitch_front2
Photo 1: front, not stretched. Photo 2: front, stretched.

stitch_back1 stitch_back2
Photo 1: back, not stretched. Photo 2: back, stretched.