What causes DNA gel electrophoresis bands to swirl?
It can possibly be one of two problems:


Either the gel poorly prepared, in that it was cooled for too long, resulting in parts that solidified before pouring it into the mold.
This I have seen before, the pH of the electrophoresis buffer and the buffer used to make the gel was not the same. It has to be the same throughout the gel to ensure that the DNA moves evenly to the positive electrode. 


Do you perhaps have a gel image of the bio-transilluminator? It could provide more insight.

Hope this helps