Strange boot sequence with new HD

I cloned old HD with SuperDuper! and then installed new HD. Everything works well except during the boot sequence. Before the gray Apple icon displays, I see a small folder with a face (I think) and then a "?". A few seconds later, I get the gray Apple icon and the boot sequence returns to normal. I've unplugged the external drive so the computer shouldn't be choosing a boot source. Any suggestions?

I found my stupid mistake. I hadn't selected new HD as startup disk in System Preferences. Now, it works very well.