Hi Patches-4
Yes, this happens quite a bit. If you have paid for your cruise in full and the price is lowered you will get the price difference refunded to you in the form you paid - i.e. it will go back to the credit card you used to make the final payment.
If you have not paid in full the price difference will just be deducted from the cruise total and will be reflected in your new balance due amount.
John