Only thing I can see is that you it seems like you were looking for someone to craft the helm. Therefore, it was probably the blacksmith that responded to you. And as thus, I'd say it's your responsibility to tip appropriately.
However, it does sound like the guy was being a total douche, and demanding a tip is then therefore not a tip. If it was agreed ahead of time, like he responded that he could make it and tips are appreciated, then it would be your bad. But I highly doubt it's the case.