I had some knocking noise in the rear and traced it to the rear driver side strut. It only has a little over 17K miles. Thought it would be weird for the strut mount to go out but went ahead and got one from the parts store. Pulled the strut out and went to have the strut mount put on. After the guy had it on the spring compressor, he pulled it apart and discovered that it didn't have the little tube spacer. There was no sign of one ever being in there either. It has never been replaced before. I heard the sound when I first test drove it but shrugged it off thinking it was the tire inflator loose. I guess the previous owner shrugged it off. It was an easy and cheap fix but still, not acceptable. NE-ways, has anyone else had this problem? Kind of makes me made to think that the factory would have left this little piece out. I am a newb here so please tell me what other common problems will I have?

TIA,