In my experience I have, to date, only heard queen piping when a new queen is about to emerge from her queen cell, or has emerged from her queen cell and is wandering around.
When I look at that frame full of capped brood, what I'm 'not' seeing is eggs. Eggs would tell me that there has been a queen around for the last 4 days. I'm wondering if she took off laying like a boss and then something happened to her soon after.. or for some reason she was superceded and now you have a new virgin in there.
Now this is my own bee math, math is sketchy with me... sooo...