Zoe - you can use the search function to see what string heights people recommend at the first and 12th frets, but there is not a consensus on that. Some like em lower and some like em higher. Most manufacturers set them too high on purpose to avoid buzz with all kinds of strings. Lowering them is mostly a matter of sanding and/or filing as RevWill is alluding to.
That said, I would say if you don't feel you are having to push down too hard on the strings to get good tone and to play the kind of music you like, I would check the intonation with my chromatic tuner by fretting each string all the way up to say the 12th fret or more. If the intonation is right, each note will be spot on a semi-tone higher than the next lower fret. On the G string, for example, the notes should read G,G#,A,A#,B, etc. Most ukes will have some variation but one with too high an action will be too sharp on the notes as you go up.
If you are happy with the intonation as described above, and you are not getting any buzzing, or having trouble playing it because the strings are too high, I would say its fine.
It would be intersting to hear some of the retailers weigh in on this, but if they told us how they do it, they would have to kill us to preserve the secret methods.