My doctor said that you should stretch after the workout because muscles are contracting during the exercises (of course they also are being broken at some point) and you should do some stretching t bring them to their previous state, I hope I remember correctly what he said. I would reccomend you to consult I with a doctor who has some knowledge about it, cause on may say this, an the other can say something different. This is what I was told and I'm doing what I was adviced to do. Also I've read somewhere such comparison, I don't remember where exactly, that working out is similar to the work of blacksmith. Your body is the iron, and it must be heated before any work on it (warm up) and after the work is done it must be cooled to maintain what wasade to it during the workout (stretching). I believe that this is how it was said/written, so I see no reason why not to stretch after a workout, but again: consult it with an orthopedist.