A personal moral dilemma

I'm house-sitting while my parents are away on another of their Elderhostel weeks. It's a simple enough task, as long as I don't try to make turkey soup. Still, they left me no emergency instructions other than "don't burn down the house, and leave some food for us".

Now, this morning, I am the proud recipient of an express envelope labeled "URGENT". It is addressed to my father, and it is from an undisclosed location not linked to Vice President Cheney. I don't think they are expecting any packages, this week. I'm pretty sure they did not order anything perishable to be delivered while they were away. I'm also fairly certain it's not toxic or explosive (Dad & Mom have no enemies, unlike their eldest daughter). If it were emergency supplies of medication, they would have come through the local pharmacy, and nobody called me from there.

Hmm. I've squidged it around a little -- enough to know its contents are totally flat. It's small and very flat, but somewhat flexible. Did Dad drop his debit/credit card somewhere on the journey, & somebody shipped it to him? No. Mom would have called to tell me to look out for the replacements. Or would she? She is, after all, on a vacation, and when one goes on one of those, one leaves the larger portion of one's common sense at home.

There are so many other possibilities -- medical test results, insurance cards he would need in an emergency, unclaimed pawn tickets from an old classmate, paternity suit papers (snort guffaw), a thin-crust pizza... from the genuinely serious to the "why did they bother mailing this?" end of the scale.

So. Do I open this big cardboard envelope, even though it is not addressed to me? Or do I leave an "URGENT" object sitting on the dining room table until Saturday night when Dad is expected home?