As I understand it, some trucks had a connector put on backwards, which puts the live portion closer to grounding out on something near the connector. No big deal normally, but in a wreck (???) it makes it more likely to short out and cause a fire. So basically, if yours is on backwards, they flip it around the other way.
Takes only a few minutes; if it reduces the risk of fire even a little bit then to me it is worth the time. As noted, this is a Safety Recall and as such there is no charge to the customer at all.