Hey Annette,
There's a difference in feel between a "tight" muscle and a "pulled" one....often, a "pulled muscle" then contracts tightly as a "reaction" to being pulled (think of stretching a ruberband and then releasing it), or if it continues, results in a "tear"(stretching that rubber band until it breaks)...to try and stretch it out is to "tell" the muscle to protect itself more...what you want it to do, is release it's "reaction"....often times, (right after injury), is to actually contract the muscle as tight as you can for a second and then release that tension, and do this a couple more times. But what I'm really referring to in the article is the next day/week after injury...the muscle will have been over-stretched and needs to regain it's tone. You will know the difference, in that the next day/week/even several weeks, the pulled muscle will not "work quite right" different sort of feeling than "muscle fatigue" or soreness due to training. A truly pulled muscle (think in terms of sprain/strain) needs rest first, then rehab. Think of "pulls" in the same realm as "tears"...if the action that caused the Pull is continued, it will result in a muscle/tendon/ligament tear.
If the muscle isn't "pulled" and is just "tight"(this is the normal course of action as muscles "fill up" with lactic acid during use)...then yes, stretching it out will feel fabulous and the correct course of action. One of the main reasons I advocate stretching AFTER a run is really to keep those muscles from getting "too tight" as a result of a work out, and it aides in the rebuilding process. In the case of "strengthening" a muscle pull, the action itself will provide some stretch in the "normal" range of motion of the muscle. And as rehab continues, light stretching AFTER strengthening is advisable.
I hope that helps.
Nate