Makes little difference AFAIC. As they are being sent at letter rate there is no seller protection, and if the items are listed as "free postage" it could be argued that there is no excess postage to refund.

Anyway, the proper time to be querying this is prior to placing the order. Contact the seller and ask if they're prepared to send all 3 items in the same package at a reduced charge, but with retail prices of only $4 I can't imagine the seller would be getting rich in a hurry.