This had happened to me the other day. The block might be blank, then it takes long for that to pass, then the following blocks come in and then yours will pop up one confirmation. Don't worry as it scared the life out of me that my client was screwed up, but it came through.
Don't worry at all, it will come or leave
It took nearly two hours for mine, so I am giving you an estimate time line that it might take. Might take less or more.
A bitcoin guru helped me with it, and confirmed it was a blank block, so that's how I found out and I used my patients.