Yes. But I don't usually stretch, unless I feel particularly stiff. An idea that you often see in sports and fitness is the idea of a dynamic warm up, as opposed to what's called static stretching. Static stretching is basically when you takes a body part a stretch it by pulling or by using gravity, like what most PE classes do, toe touches, stretching the wrist by pulling with the other hand, etc. A dynamic warm up would warming the body using actual body movements, like arm rotations, squats, walking etc. The idea is that since the purpose of a warm up is to, well, warm up (increasing the blood flow in the muscle that will be used) it's better to start with a dynamic warm up, then do static stretches later that if needed.
I believe that guitarist's and other musician's are basically athletes, we move ourselves in a certain way and in a controlled manner, so I think we can learn a lot from athletes. I usually start with simple scales, basic RH arpeggio patterns and some rasgueado to warm up. If I need to stretch my fingers, I do it by playing some stretches on the guitar (taking from the idea of using the actual movement to warm up). Only then would I do static stretching if I feel the need to.
Another thing that I do is to make sure that both the hand flexors and extensors (the muscles that close and open the hands) are warmed up. That why rasgueados are part of my warm up. So far this kind of warm up has worked for me, and it usually does not take that long. 10 minutes seems about right for me.
Disclaimer: I do not have any qualifications in physiotherapy or sports science or anything of that nature. This is all from experience and observation, plus some research.