i think "self-healing" has always been a misnomer. my "self-healing" mats do deteriorate with use. my idea is to just turn them over for extra use, although the grid lines and ruler won't be there. i also think that all mats are forgiving, and they protect surfaces for a long time - just not "self-healing". AND...you didn't mess up! i think they finally realized that "self-healing" is not exactly what they do.