Is there a reason for me to worry about the squeaking sound produced by dental crowns?

I had around 20 porcelain dental crowns placed in the front of my mouth a couple of years ago, and I've noticed that they occasionally make a squeaking noise when I stretch my mouth or lips. I diligently wear a night guard at night and maintain good oral hygiene. It seems as if they might be positioned closely together and could be rubbing against each other due to pressure. I've mentioned this concern to my dentist, but they reassured me that the crowns are well-cemented and there's no need to worry. However, I'm quite anxious about my dental health. Could you please advise if there might be an issue?