My future husband borrowed money to pay the hantaran. Should I be worried?

It deserves attention, because that debt will become a burden on both of you after the akad. Ask frankly about the amount and his repayment plan, without an accusing tone. Perhaps he did it because he was afraid of disappointing your family. If so, this is a chance to discuss the hantaran amount again with the family. A household that starts with unnecessary debt easily comes under strain, especially in the first year. Consider a smaller celebration, and get debt management advice from AKPK if needed. His attitude when discussing this also shows how he will manage the family's money. See debt before marriage.