California - Do Southern California Citypasses really expire?

The Southern California Citypasses are supposed to expire after two weeks. My family used the Citypasses on a recent trip however we did not attend one of the attractions on the Citypass. There is a place on the back of each Citypass where you are supposed to put your name and date, but we left the date blank and we were able to use the passes.

My question is, is there any central place that records when you first used a Citypass? Or will they still be valid if used after the two week expiration date?

I believe that the dates are tracked through the barcodes, and that your signature on the passes is an agreement to the T&C, and doesn't impact the expiration date - otherwise everyone would write the wrong date. It may be one of those things where YMMV though.