If you worry, you should worry from the moment you gave your laptop to someone else. It is completly unncessary to swap the hard disk to get your disk data, deleted or not.
That being said, it is possible (my speculation), although unlikely, that your hard disk has been imaged to another disk, and the fix was done on the imaged disk, so that in case the fix went wrong, the engineer can start it over.
By the way, wasn't your password list encrypted? If you really worry about your personal information, change your password and save them with strong encryption from now on. You can do encryption for a file, for a folder or for a whole disk, and there are special tools for managing passwords.
