u should have gotten a letter!
yeah i got a letter from mazda about a year ago about that problem, it was a recall. It was only on certain engines made at one plant during a certain time! They gave me a list of VIN numbers, or a range, and that if youre vin was in that range then there was a possiblity that that the screws on youre intake butterfly shutter valves were not "tightened to specifications." Luckily my engine was not made at that location, but still you were supposed to take it to mazda to get it lookedat/fixed. I got a whole new intake! Even though mine was not affected. So yeah if i find the letter with the vin numbers on it i can post it later.