Thanks all for the information.

In my past experience (we have used this exact same car seat at least 4 other times), airline usually tries to leave the seat in front of us empty, perhaps for the reason that the person cannot recline. And we certainly did not intend to cause the problem, just following directions that came with the car seat on how to properly install it on the plane.

In fact, had the person in front asked us nicely, we might have turned it around anyway since it's a red eye flight, and being parents we both understood how important sleep is.

Like I said in my OP, I was trying to get clarification on this issue from other experienced travelers, and sounds like there are some FAA regulations around the issue, and the airline should be informed.

Thank you all for your replies.