Bought in 2003 brand new, maintained.

Bought in 2003 brand new, maintained meticulously by dealer. Transmission wnet bad at 66,000 miles(2010), new transmission put in it went bad at 74,000 miles (2011) 3rd transmission put in. Dealership could not give me a good answer.I asked them how this could happen when I brought it always to them for service.I don't know anything about car repairs so I trusted them. The only answer they gave me was it happens.3 transmissions on a car with less than 100,000 lies, driven an aver age of 9,000 miles a year. Brother in law has a honda from the same year has 102,000 miles on it no transmission problem. Is this car a lemon and the dealer won't say or is this a common problem with this model?