update needs review and it takes quite a while

I don't think I ever saw the message that an update (of an approved app) needs a review, but this morning ~8h ago I've published an update and since then it shows the message
"Please note: This app has a version update pending. Changes will not be visible until the approval is complete. This process could take up to 2 hours."

Did I do something wrong in the update or is that the norm?