Automatic Transmission problems of the 2008 Mazda Tribute

I took my 2008 Tribute (purchased in July 2007) for service when at the 50, 300 miles. I reported to the service department that my vehicle does a mild or hard jerk when coming from a complete stop. It was discovered that I had a small hole in the condenser causing the vehicle to lose transmission oil. I do a lot of highway driving thus the high mileage so they surmised that maybe a rock hit it. I thought this was outrageous because this vehicle was suppose to be durable since it is a SUV. My driving is not in rough terrain just smooth highways. The service department pointed out to me that the style has these exposed or open areas in the front lower part of the SUV so because they saw a tiny rock embedded in the grill of the radiator that possibly this is what happened to the condenser. I felt if I have exposed or open areas then the parts exposed should be strong/durable enough to take a rock hit. I have no front in damage and I have never been in an accident. A transmission oil leak was the farthest thing in my mind, which by the way will cost me $580 to fix. Since this discovery was on 12/15/09, ten days from xmas, I did not have it fixed. My fear is that there are substandard parts that were put on my vehicle because I feel that the parts should be durable enough this is an 2008 vehicle I bought brand new so it is not an earlier model and this did not happened from a lot of wear and tear. Please look into this model for substandard parts. I just knew that I would have this vehicle for a few more years before any major work was done.

Transmission cooler line leak.