How often are you checking? The reason im asking is that the cervix can change several times during the day even. If you're really worried id check with the doctor, hun. Its better to haver peace of mind than worrying about this. There are some studies that suggest the possibility of a weakened cervix with repeated d&c's (and abortions, as essentially the same procedure of opening the cervix is used) however, this data has not been thoroughly verified and many women go on to have healthy pregnancies and deliveries after several d&c's (4 etc.). I myself had 2 d&c's in a year and have not noticed anything different compared to times i checked in the past.
To answer your question directly, no i haven't heard about this but short of actually looking at your cervix directly (i.e. a scan wont do) there really isn't any other way of telling.
I hope this is just the way it feels to you and nothing else. Sorry for no better answer, chicken. And good luck!