Snake oil will do that<img src=http://www.ezboard.com/images/emoticons/wink.gif ALT=";)"> . Seriously, though, if the repair was done abd finished correctly, it should have held up. I purchased my initial kit used. It did not include pit filler, nor did I receive instruction on the proper way to finish a pit. My "trainer" (a-hem) showed me how to remove the bridge/injector assembly and use curing tape to corral the resin that runs out, so that the repair resin also is used in place of pit filler. I was a newbie... what did I know? However, when my own windshield developed 'freckles' , and the sun-burnt resin flaked out of the pit, it occured to me that there must be a better way. I found forums similar to this one and also many suppliers willing to share their knowledge and experience, and I quickly learned better methods for finishing the repairs.
You are on the right track, asking for advice from the people in these forums. I wish you success in this business.

</p>