Defendant Needs to Object to Conflict of Interest

In People v Peterson, 2008 NY Slip Op 03822 [4th Dept 4/25/2008], the Court held that where a defendant contended that County Court failed to engage in a sufficient Gomberg inquiry when the court learned that defendant and a codefendant were represented by the same attorney (see People v Gomberg, 38 NY2d 307, 313-314) the "Defendant failed to preserve that contention for our review (see People v Woods, 6 AD3d 1126, 1127, lv denied 3 NY3d 683...." What duty does the Court have to point out the potential problem to the defendant?