Murphy's law: the instrument that would have been most appropriate to that wonderful session is the one you've left at home! (I play several instruments so can speak from experience!)

Ah it's so reassuring to find that happens to other people ... but even worse was the time at a festival last year where I'd hawked the instruments around Friday and Saturday evening without so much of a sniff of a decent session, and so found myself listening to a great tune mashup on the Sunday night whilst the concertina and the flute bag were keeping the dog company in the B&B several miles away ...