Well this morning I went to abc.com to re-watch that episode and double check it.
After a few too many 30 second ads for Hamburger Helper I found it - at about 46:35 (not sure if it's the same timecode on the DVDs, they might excise the "previously on Lost" bit).
It sounds like an overdub, and Kate is saying something else at the same time, but it's there. I swear to you.
Here are some screen captures, in case you too want to go scout for it yourself ...
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