um ... hills and mopeds don't really get along too well. how steep was this hill? if it's steep enough, you will have to pedal up it. as long as it runs fine on other surfaces, don't worry to much about it. though you could get some more power w/ a larger carb or performance muffler.
remember that you're riding a 1hp engine. it's not really meant to go up steep hills. amen for pedals, though! ;-)