I would stop misting the plant and not fertilize it again until it's well settled in. Misting doesn't do anything, and you only fertilize when the plant is acclimated and actively growing. The brown spot on a new leaf is a bit worrying, but over all the plant looks just fine. I wouldn't fret unless it spreads or the plant declines. A brown spot or a little brown edging here or there isn't unusual and may not mean anything.
