Be sure you're getting a really good stretch and holding for at least 60 seconds. It should be rather painful, but muscle pain from stretching, not joint pain...you know.
The extreme stretching is very key to recovery. I have been pressed for time in a workout before and in my haste had forgotten to stretch triceps once and hamstrings another time. Boy did I feel it over the next few days! I could totally tell the difference, and recovery was much slower.
If you are doing one of his prescribed stretches and aren't getting a good stretch, you can also change it to a stretch you can feel and you know you are getting a good stretch. I had to do that with the quad stretch. There are a couple variations of the tricep stretch that people seem to be split on too.
At your level of training you will know what is working for you.