I can see why you grew tired of it - it's not exactly an inspiring piece and there are some really fiddly sections as the piece progresses.
The first minute went smoothly, then you seemed to lose concentration a bit, but if you're not enjoying the piece it's understandable why your brain might be desperate to wander off somewhere more pleasant! That's how I was at school, during maths lessons... my brain just refused to operate in such a dull situation! I think you did well to plough through a lesson that wasn't enjoyable, now you can move on and play something more enjoyable.
"Don't let's ask for the moon, we have the stars." (Final line from Now,Voyager, 1942)