Upvote:1
Asked the CBP about this a while ago, and you don't need a new ESTA, but should update the details in your current ESTA that can be updated, if any (don't know how it works if you selected transit, but otherwise several details, such as what address you're staying at, can be edited).
At most airports you can now use a kiosk (automated passport control) instead of filling out the blue form. The kiosk will ask in what status you're seeking admission (WB for business, WT for tourism).
Such situations are common, so the officers are used to it. You'll be fine!