Yes, there were some changes. The 03, and all prior years, have the big bolt, the 04 and some 05's have the little bolt. I believe the 06's will all have the big bolt. I had mine back out too but luckily noticed it one day before starting the car while checking the oil. Lucky, you bet. Red loctite and a torque wrench, no issues since - about 15,000 miles ago.
Hope this helps.
Dan