Email to Pat and others
Strange question - anybody happen to be missing a pair of black pants? They were in the 4th floor conference room today after your departure.

Response from Pat
I'm embarrassed to say that would be me-- I really like those pants so I thank you for finding them (and for sending them back to their careless owner).

I was going to say not to worry I wasn't wearing them when they were lost but that sounds really bad. How about, I just say I think they must have fallen out of my backpack when I pulled out my jacket?