Shortened Cervix

Went it for an appointment and they told me my cervix was 1.5. The dr wasn't happy I feel fine no contractions at all. Haven't been placed on bed rest but it was shortened before at 18 weeks measuring 2.5 & went bk to normal. I go in in 2 days for test of fluids for early labor. Anybody else experiencing things like this I'm 30 weeks and my babies are 4lbs.