This seems eminently, well, normal, at least to me:
I’m also having a little easier time with some of the piano stuff. Maybe these things go by cycles? Maybe for a while you are just kind of dull and stupid about things, and then that resolves, and you get better at it? I never seem to progress at anything smoothly — I struggle for a while and then suddenly it becomes easy for a while until I struggle again.
Just about everything I’ve learned has dragged me through that particular pattern: up a bit, a plateau, up a bit more, lather, rinse, repeat. Perhaps they call it a “learning curve,” not because it’s necessarily curved, but because it’s so seldom a straight line.