I am on the northern edge of the zone where Centipede can survive winter. It does not go completely dormant here. Neither does St. Augustine. Both are stoloniferous turfgrasses so most of the plant parts are above ground. This is also why they are not cold tolerant. If you get down and pull the turf back, you will probably see lots of green.
Years ago I made the mistake of spot spraying R-up in zoysia which also doesn't go completely dormant. It knocked the turf for a loop(heavily thinned) in those areas and took some time to recover. Zoysia is slow to recover though.
IMO, at the very least, you've knocked the turf for a loop. Worst case scenario, you smoked it.
That's why professionals carry insurance. Good Luck.
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