The very same thing is happening to me, but I think it will be OK.
I had booked our tix on USAirways' website a while back, and like you, I chose seats right then and there. I even got an email confirmation from them indicating my seats. (We are traveling with three kids age 5 and under, so it's important that we sit together). Like you, I checked my status online a few weeks ago, just out of curiosity. Suddenly, it said "Check-in at airport required".
I called USAirways and was told that I would need to deal with it at the ticket counter or gate on day of flight. I didn't like that answer so I called back the next day and spoke with someone else. He told me that their system showed only 3 seats assigned, although we purchased (and selected) 4 seats! But he said there is nothing we could do until day of flight. I didn't like that answer either so I called back again the next day. Finally, I got someone helpful who put me on hold while she fixed the situation. She assigned us 4 seats together on both legs of the roundtrip (better seats than we had originally).
Still, the website says "check-in required". I even called a few days later, spoke with someone else just to confirm that my seats were locked in. They are. And after reading your post, I check their automated phone system and my seats are still locked in. So, I'm deciding not to worry about it. I'm going to try to use online check-in next Friday afternoon; hopefully it will reflect our seat assignments. If not, I'll deal with it at the airport.
My experience with USAirways is that while their ticket and ressie agents are always courteous, it is really hit or miss as to whether you get someone who really wants to help you. Unfortunately, there is not much competition for them in flying out of Pittsburgh.
Good luck, I'm sure it will work out just fine.
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