I didn't warm up either other than play, until I really ended up in the same boat as funkadelic. Went from average weekly play to 3 hours a day for 4 weeks preparing for a rock show with a lot of solo work, and it hit me hard by the second night of the show. Got through the run on Ibuprofen and ice packs, and had to rest my hand afterwards for a while.
In my case it's probably exacerbated by years & years for riding bikes, especially 3 years in the saddle full-time as a London despatch rider. Running a clutch in heavy traffic for up to 8-10 hours a day didn't help, and neither did a few falls. The worst saw me off at 80-odd, when my bike washed out to the right and as I rolled off, my left thumb bent back nicely under the handlebar. I couldn't rest it, and two subsequent injuries in later years to the same thumb mean that if I DON'T warm up, I can't do more than a minute of barre chords without serious pain in the thumb joint / muscle.
The Petrucci video's a good one, as is this one. =
The guy does some decent tutorials as well.
I combine both videos' advice for warming up and give myself a good 15 minutes to do it. You can also take a look at these posts from the Seymour Duncan blog on the subject.
http://www.seymourduncan.com/blog/the-players-room/hand-health-coping-with-carpal-tunnel-and-arthritis-as-a-guitarist/
http://www.seymourduncan.com/blog/the-players-room/preventing-disaster-carpal-tunnel-tendonitis-and-hearing-loss/