When I had my doctor renew my Ambien Prescription the pharmacist said he could not fill it as there was s 3 month old filled prescription waiting for me to pick up. I said fine and picked it up. I travel out of town quite a bit and it seeks that since this prescription I did pick up was filled 9/10/2011 I should be able to fill the refill just about any time I want to, since the thirty day fill is long past, and I do not believe the pharmacy notes when a prescription is picked up but simply when it was filled. and use that for when I travel on trips and have a tendency to forget stuff
Stuff like including a question in your post? 
Maybe the Ambien kicked in.
Been there, done that, forgot watching a whole movie (Sweeney Todd; don’t remember a single scene).
Yes, you should be able to refill it any time after the 30 days, if it was a 30 day script. I have one that’s 90 pills / 90 days, and I have to wait 3 months to fill it.
Oh, and a pharmacy definitely knows when you pick up a prescription. You gotta sign for it! You either sign an old-fashioned pen-and-paper log book, a paper slip (which is also dated) and retained by the pharmacy, or you sign an electronic pad.
~VOW