Short Cervix At 24 weeks .. Nervous

Christina
Hi ladies... 
I had a sono today , I was told my cervix is a little short measuring 2.7cm when normal is 3-3.5 ... I go back in a week to check again .. I pray it tightens back up!! 
I was very active on my feet this weekend cleaning and decorating because I had so much energy, maybe I over did it?
Anyone else had this happen to them?