I've recently noticed my spine has lengthened at almost 23 years of age. does the spine/torso grow last during puberty?

No: The spine continues to grow at its most rapid pace around the peak height velocity—this is different for every person. Long bone growth and spine growth seem to end about the same time. Thus, you stay proportional during growth. At age 23, you're likely noticing something other than growth as you are well beyond puberty and the phv that predicts completion of spinal growth.