It happens to me that when I go for a run, then my body does not really feel like stretching. Then, after an hour or so, I can do that and it relaxes me a lot.
Also, I may be somewhere outside during the day and have some time to 'kill': waiting for the bus, watching to my kids, etc. Those are kind of boring moments of the day where I feel like stretching, and I do it. Mostly, I stretch my legs muscles, such as quadriceps, calf, and others.
For this, I wonder: is it good for the muscles to stretch them randomly, from time to time? Do this increase the flexibility over time? Is there any risk in doing so?