CoolSculpting had pop off after 16 minutes

Once there is a pop off, the treatment should be stopped and the area should be retreated. The targeted areas should have the full 35 minutes to complete the treatment. 

As a practical matter, a Coolsculpting cycle is considered irreversibly underway after 5 minutes-so the option is to repeat the cycle or not.  While 16 minutes may give adequate treatment, ideally, the area should be treated for the full cycle.  Allergan is very responsive--and so if there is an incomplete cycle, your provider can discuss getting that incomplete cycle repeated.
Theoretically, the full treatment would be the ideal time to allow for adequate freezing of the fat tissue--and combining shorter cycles will not give the same cumulative effect as a full cycle.