I booked AY5/6 through aa.com, and tried to select seats with AY record locator found on my e-ticket. The seat selection button is gone indeed, but I somehow managed to get to the right page by using the link for adding TSA information. I selected seats and confirmed them, but the site never asked me to pay for those seats (I am AA GLD = OWR). Checkmytrip indicates that my current seat selection is confirmed. Does this mean that I got these seats for free, or are they going to ask for money at the airport?

Strange thing: AA.com shows that these flights have been replaced with new flight numbers, AA6025->AA8985. All the details remained same. I noticed this today, maybe they are only messing with the codeshare flight numbers?