Check out this great guitar lesson post on finger speed for lead guitar. I also learned (still learning) the guitar later in life. I picked it up when I was about 18 and didn’t really get into it until my late 20’s and have had the same hand stiffness problems. Practice more, stretch, and lots of alieve is what saves the day 
I visited guitar5day.com today and liked what I saw lots of guitar lessons and techniques on the blog and main site. Definitely worth checking out if you are learning the guitar. The site promises: “You now will be able to improve your guitar playing with our Rapid learing Guitar lessons. For four years I have been a leader in guitar speed learning. Over 13,165 customers have seen rapid improvement. Now you can learn on your schedule. Short yet powerful lessons and exercises teach and re-inforce the critical building blocks to succcessful and enjoyable guitar playing. ”
3 DVDs are available from the site. The video on the homepage is a bit strange with his daughter talking though the whole thing, but it’s cute I guess.
I especially like the Guitar Solo Octaves post. Nice work.