Sounds like he got a dose of his own medicine.
Not really. Tiller went fast. He did not have to feel the agonies of the partial birth abortion technology he inflicted on his victims. He did not have the base of his skull pierced by an instrument, and then have his brains sucked out until his skull collapsed.
OTOH, it may have been a head shot with a large caliber bullet. Even so, that would have been quicker and less painful than what he did to 60,000 innocent babies.