I had heard this was a possibility, but on my four AA flights this week, all domestic in F, no one, including myself, was refused entry into the washroom. The only restriction we were informed of was on a flight ex-DCA, where we were told that nobody would be permitted to move about in the cabin -- but only if we had to get somethng from the overhead locker or go to the lav -- until we had been in the air for 30-minutes.