A: That label represents the day the were received. Those cigars should be really smooth by now. Open the box, take out two cigars and let them sit for a couple of days in your humidor. I have a feeling they will be quite nice.
Re your second question: Since Lanceros are not as popular as the fatter cigars, that’s probably why they’ve had more aging time. And yes, there is a difference, but not with regard to the blend itself. The Robustos at 5½” x 50 ring are going to give you more overall flavor and aroma. With the Lancero at 7″ x 38, you’re going to get more wrapper flavor, and those Rosado wrappers happen to be quite good. So, if you’ve smoked a lot of the Robustos, you will notice a difference in character, bouquet, and maybe even strength.