Same here except our original plan for our 7-day Med cruise was 11 days abroad, which stretched involuntarily into 2 weeks because we lost our Passports and it took a few days to sort it out. Our next long one is a 12-day British Isles cruise in May and we'll be holding onto our papers for dear life!
We allowed ourselves about 5 minutes to completely lose our minds but then agreed we needed to get it together and not let it ruin the rest of the cruise (lost them on day 2). Everything worked out fine, as most things usually do, but it was inconvenient and expensive.Oh, I can only imagine the sense of panic when you couldn't find them.
I don't know when the cruise lines changed the policy (maybe after 9/11) but I remember handing them my passport for the Med cruise and getting it back when it was over. Seems so weird now that they held them, but they did.