Cir. 1998) (recognizing that "a party may raise jurisdiction at any time during the pendency of the proceedings"); Harrell & Sumner Contracting Co. I. Peabody Petersen Co., 546 F.2d 1227, 1229 (5th Cir. 1977) ("[U]nder Rule 12(h)(3), Fed.R.Civ.P., the defense of lack of subject matter jurisdiction may be raised at any