Cervix funneling at 20+5

At my anatomy scan my cervix is slightly funneling and cervix thickness is measuring 3.3. My dr don't like to see anything below a 4. Suppose to take it easy and recheck via ultrasound in four weeks at my next appointment. Any one have a slight incompetent cervix and Carry to term(37+weeks)? If not what was your experience? Baby is perfect and measuring great.