Ah yes. The all day cap for zones 1-4 is £11.00 so you didn’t actually reach it that day.
And yes, the pink readers at Stratford are on the platforms served by trains from Hackney. I think that’s 1 and 2. Annoyingly a small number of trains use platform 11 instead so you’d need to go back to touch the pink reader if that’s important for your fare.