I guess expectations vary, but I agree here with other comments, that is only cosmetic, will not affect the integrity of the mold, nor how it will pour, so I don't see this as any problem. I qualify my comment having poured for over 50 years, and I own a lot of molds. I own most of the mold styles that Do It has ever produced for pouring lead. I don't pour any soft plastics.
I also don't see this as a quality issue. Do It Molds produces hobby molds, and that mold will do as it's intended. They do not offer any warranty or guarantee that every mold they produce will "look good", they warrant that the mold will do as it's intended, which is produce a hobby use result.
I was just in a discussion about this, with folks complaining about Lee melting pots, but too many also complain about Do It Molds, as well as other things.
Most who complain are trying to operate businesses with products that are not intended for commercial production. Yet, they purchase these products with a much higher expectation than is reality, because of the price. For the price tag Do It Molds are the best on the market.
If this "blemish" is a big concern, then certainly contact Do It or the seller, and see what can be done.
Your other option, is to have all your molds made to order, custom CNC cut by a mold maker, but that's going to have a much higher cost involved. But, then you shouldn't see any blemishes.
IMO, too many folks now want to pay for zirconium, and expect diamonds!
