What Causes Tightness In The Cervix?

On my last 2 pap tests I have been told that my cervix is very tight. So much so the doctors had problems doing the test. This seems to be an issue in the last few years. I did have a D&C a few years ago. Could this have caused a tight cervix? Could it just get tight on it's own? Is there any cause for concern?

Thank you!