I've have the exact same crack in my panel since I bought it. It hasn't travelled at all, but I like the idea of drilling a small hole as a preventative measure.
I'll be doing that once the weather warms up in about 5 months, or maybe sooner if I notice it getting worse.
I figure epoxy on the back of the panel to hold it all together, and some kind of plastic panel repair kit on the outside should make it as good as new.
Unless of course I can just find an intact gray panel at a scrap yard to throw on there.