I haven't heard of enough issues to have it cause concern for me (yes -- there have been issues but when you think of the millions of bands that have been distributed it is probably not a huge percentage with issues) but I am sure that you can check at check in. If you take ME, I believe that will be one opportunity to use them and then for your room and then the parks unless you buy something with it before you head to the parks.
I used them back in November when they were newer and we had no issues at all and we are AP holders.