The kiln operator modifies the moisture content at the end of the drying process, and ideally, there would be no remaining stress.
However, the irremediable state of reverse case-hardening must be avoided, so a bit of case-hardening is acceptable in the final state of most kiln-dried lumber, demonstrated by a slight inward curve of the tines of a test fork sawn from a cross-section sample of the board (below).
8/4 is, of course, much slower to dry than 4/4, white oak is a relatively difficult species to dry well, and quartered lumber is a bit slower to dry.
Further, since 8/4 white oak is less common, this board was probably lumped together in the kiln with thinner lumber and/or faster drying species for which a faster kiln schedule would work.