Cutting board from previously stained wood

I purchased some lumber from a third party which included a large walnut slab that had previously been stained on one side (I don’t know what it was). I wanted to turn it into a few cutting boards, so I cut it into pieces and passed them through my planer on both sides until it was flat and all stain was gone. Is safe to use as a cutting board, assuming I am going to oil it with mineral oil?