Dude -- you won. They stuck with their "process" and refused to pay you what you were worth. You found someone who did. And then they finally were to realize that you were a massively good deal and now they have to offer tons more money just to find someone who is both able to do what you did and willing to put up with their toxic environment (and lose even more money/efficiency in training them, too). So, basically, your old management gets to suffer the giant sucking sound of profits going down the drain because they didn't meet your eminently reasonable requests. Meanwhile, you are out of that environment, with the title and pay you deserve, and you never have to devote even a millisecond to thinking about those losers ever again.
This is a referendum on them, not you. I would think their job posting reinforces what a good decision you made in leaving, as it amply demonstrates that your old management is petty, short-sighted, and too stupid to figure out they've got a good thing until they chase it away, yes? I'd work a little more on your gloating skills if I were you. Repeat after me: "I told you so."
FWIW, I know from resenting. Ask me about DH's company, which moved us across the country to their most profitable fab, and then shut it down when I was 6 months pregnant so the Big Boss could meet certain post-merger financial targets that made him eligible for a nine-figure stock grant. No one on earth has ever been happier than I was when Big Boss went to jail a few years later for diddling the books. Karma's a bitch, and so am I.