@goingnutsmom If you take a look at the common data sets for the top 20 colleges - about 30-40% get FA. It is pretty consistent across the board. Yes, WashU is need aware. Obviously, they all must be even though they say they meet 100% need - since they consistently give 30-40% FA year after year. They are a business so they know how to run a tight ship.
@cappex Congrats on your interview! Good luck too! WashU has over 29k applications for roughly 1700 spots. Unfortunately, it is very difficult to get in and yes they will turn away students with high and/or perfect stats. Its simply because they cannot accept everyone. All you can do is try and show interest (which you have). 