السلام عليكم ورحمة الله وبركاته أحسن الله إليكم، Ustadh, if there are Korean cheese-flavored noodles and I don't know whether the rennet used in the cheese is from a halal source, even though the product has a halal stamp, would it be considered digging too deep?

Yes, this would be digging too deep. The asl (the default ruling) in food is that it is permissible, and you are not required to ask about every ingredient like the source of the rennet. When the product even carries a halal stamp, the matter is clearer still. Unless he knows for a fact that these halal stamps are fraud.