That seller is a big outfit and is usually pretty good. I had a bit of a problem with him recently when I tried to get an invoice after there were problems with the listing for one item I won (out of four) but he apparently didn't see it and posted unpaid-item notices when the items had lingered over a week. It turned out just fine once I got his attention. I was a bit slow in following up because I was out of town, including a visit to the Philly Show in Allentown. The seller posted the unpaid-item notices right after he got home from ... the Philly Show in Allentown. I wish he had read my name tag.

My wrong-postage issue looks similar to that negative for the "extra shipping." His single-card auctions all say $2 shipping and he seems to let the auctions combine themselves, with no multiple-item discounts and no invoices. But when I went to check out, I found that one of my single-card items was tagged with a $7 Priority Mail charge instead of the $2 in the item description. Eventually it got fixed, and I assumed it was a mistake where he listed single cards for $2 or bigger items for Priority, and just erred in the mechanics. But I waited to pay until I could get it fixed, and I paid $2 instead of $7 with a corrected invoice.
After it was fixed, my four cards (where I paid $8 S&H, $2 times 4) were shipped and delivered promptly (7 days after payment) for a postage cost to him of ... $0.79.
For the neg you mentioned, the seller indeed messed up the listing in the same way (Priority charged at checkout vs. $2 in description), and probably he didn't notice he'd done it. He used regular 1st Class mail (as his habit) without noticing the buyer had paid Priority. The buyer apparently didn't check before paying like I did. An odd thing is that the negative was given for an auction for a sketch card, from the same artist and the same set, as one of my wins from carbud.
I note that I have had successful wins from this seller going back more than two years, with items received in 7-9 days. Previously he offered free shipping! He's never left feedback though, and seems to be slow on responding to emails. Give him an item-not-received notice and I bet he'll respond, though.