Texas_Signmaker
Very Active Signmaker
I think if the spot your friend made is somewhere that no one will ever see it and it's not going to cause any future corrosion or discoloration due to exposed metal or some such thing, then no, I don't think that merits notifying the customer or anything along those lines.
There are obviously shades of gray requiring some discernment.
This was the spots my friend made. I didn't think it was a big deal... after a week there will be bird shits larger than this.