That seems like a fairly large difference. Have you double-checked that the NPC data you entered matches your CSS Profile and FAFSA? Do you have circumstances that would make the NPC less accurate – such as divorced parents or your family owns a small business? if not, then I think it is definitely work calling financial aid and politely asking them about the large discrepancy.
And just so you know, it’s fine for parents to contact the financial aid office on behalf of their students (it isn’t fine for admissions) – just in case you think your parents might be the best ones to call.