Variation among the Verbs

There's a story floating around on various news sites about Seymour Hersh's latest words on the Bush administration (it's truly depressing), given at a symposium at Tufts. Striking, verbwise, is this sentence (quoted here from a Tufts Daily story):

Whatever Iran has, they've shown us, they've showed the I.A.E.A. [International Atomic Energy Agency].

Assuming he was quoted correctly (I know, massive assumption, but I've been quoted accurately by reporters several times), these are nice examples of morphological variation from a journalist speaking in a formal context.