At the start of treatment the teeth are at their most out of line: some are badly rotated, others have gaps, and a tooth may be largely hidden behind another one. This makes it difficult, and sometimes impossible, to place the bracket perfectly in the middle of the crown. Once the levelling stage with braces is over and most of the teeth are in line, we assess the position of the brackets and, if necessary, rebond individual ones. This is a perfectly normal part of treatment and actually saves time, because repositioning a bracket is the quickest way to correct a tooth.
This answer is for general information. Your own case needs an examination by an orthodontist.