31 weeks and got was told I'm now high risk

Went for check up and doc wanted to check my cervix since my last child I dilated 4 cm at 34 weeks but didn't go into labor till 37 weeks..anyways my cervix was closed but he said it was to soft so he put me back on the hormone suppositories till 37 weeks ..luck no bed rest yet but I am taking it easy in hopes I can keep working ...I guess I'm just wondering why I'm now high risk if I haven't dilated any yet..my blood pressure is great and so is my sugar. .