Dana, Sorry to split hairs but I'm intrigued. Are your recent pairs new stock. You can buy brand new AG jeans off ebay today that were manufactured more than a year ago. I hope that makes sense. Stock in regular stores (not outlets, discounters, or thrift stores) are hot off the sewing machine, if you know what I mean.
Beth Ann, you are spot on. Some brands are distancing themselves from vanity sizing. And Euro brands who show US and Euro sizes on their tickets and still manufacturing size 2's and 4's the size they use to be 20 years ago - which is a common size 0 today.
The sizing down in jeans will benefit some and not others. People who were sized out of a size 25 can finally fit into that size because it's cut smaller, while people who used to fit into a size 31 or 32, are sized out on the other end.
Come to think of it, J.Crew's Matchsticks are cut smaller over the last few years too. Clients are sizing up one and two sizes there to create the same fit as their old Matchsticks.