I don't know that stretching your forearm muscles
would improve your release, but it seems sensible.
I lift weights and do a fair amount of grip training. I find that if I don't stretch, my fingers begin to curl more when simply hanging and eventually I start losing strength.
While I'm giving the perspective of a weight trainer and the grip intensity may be higher that drawing a bow, shooting several hundred arrows per week (I think DA shoots daily) can put a lot of stress on the back of your hand and on the forearm muscles.
This is a very long winded way of saying "It can't hurt".