Ah-ha! It was Colonel Mustard in the library with the cupcake
Remember our family-wide bout with the norovirus? Today's Boston Globe ("Norovirus closes Harvard club") carries the news that the same culprit seems to have stricken diners at Harvard's Faculty Club on Easter. I'm going out on a limb here and assuming that the same food service that provided refreshments during our ill-fated, so to speak, visit to a Harvard's Houghton Library in January also serves the Faculty Club (otherwise a lovely place to dine, I might add; last time I was there they served fab sushi). Regardless, I hope they get it this time. Nasty little buggie.