Are Google AdWords Ads displayed based on users behavior? Will Critchlow apparently noticed this activity.

When I spoke to the account manager at AdWords, she told us that there has been a change to the algorithm to take into account your history with respect to the particular ad. Apparently this change has only come in the last few days – and I haven’t seen any mention of it (have I missed something?).

At first glance, this should be beneficial to the AdWords Advertiser because there will be fewer impressions but on the other hand , a customer may be interested in something tomorrow that they were not interested in today. Maybe an official announcement from Google will provide more clarity.