Just to second the last poster and reassure the OP, the new straps are sent out as replacements even though nintendo's website gives no mention of the change. I have received two not knowing that there was a change. From what I can gather, there is no "recall", just simply a redesign.
(A recall would imply some fault with the original tightening mechanism, which obviously places some blame upon Nintendo for stupid people's misuse. No self incrimination necessary)