Most likely, it's your fault, somehow.
In the Allocations instrument, press the "i" button and turn on "Record Reference Counts". Then Instruments can show you all the allocation, retain, autorelease, and release events that happened to those objects. (You should see an arrow next to each leaked item -- click it to show the allocation history of that object.)
I think you'll find that some of your code is retaining something, or indirectly causing it to be retained. Probably the scroll view or one of its gesture recognizers, as a guess.