Auto body repair & detailing: auto body repair, auto body shop, auto body repair

Question
Thank you in advance for your help!
I Bought a certified used car , a few weeks later I noticed an "X" shaped crack in the rear lower quarter panel.  I put a magnet on it, and there was body filler there.  The dealer repaired it for free in their body shop.  Six months later, same crack has appeared again.  Any idea why?

Answer
Sue-

There are many reasons this may happen. My advice to you is to have it looked at by an independent auto body shop locally. They are very likely to be willing to do a brief inspection of the car, on the spot for little or no charge. Tell them what happened and see if they can tell you how significant of a repair was done to the car originally. Try to find out if it was a small dent repair or a major rear end repair. They should be able to determine this simply by inspecting under the trunk, cargo area mat, or spare tire well. The car may have had significant damage, or not.
The good news is, you bought from a responsible dealer that has your best interest at heart, otherwise they never would have fixed it for you the first time. I can imagine they will be eager to stand behind the repairs from 6 months ago. I think it's smart for you however to get an independent opinion of what's going on too. Just to make sure the car doesn't have some more serious problems. Good Luck, Mark