There is a good discussion of this story over at Seeking Alpha. My guess is that this whole event is staged and is designed to send a message to someone. First, the bonds are suspected counterfeit but are indistinguishable from the real thing; they are given away by their date (1934) and denomination ($500M). $500M bearer bonds did not exist in 1934. So someone went to the trouble of producing these perfect counterfeit bonds but then stuck the wrong date on them. Second, only nations deal in such large amounts, yet if a nation wanted to move bearer bonds they could have done so through diplomatic channels without risking customs search. Third, the amount seized is $134.5B, the precise amount announced as remaining in the TARP program fund in March.
Someone is sending a message that unless the US plays ball they are going to take action, maybe involving debasing the US currency through counterfeit? Whoever did this is capable of producing perfect counterfeit bonds and could easily put the correct dates on them.