Bummer. Flats in the cold are a real PITA. Been there, done that. No T-Shirt, though.
The one and only reason I run Slime in my tubes is so I can find puncture holes. AFAIK
, it's never actually sealed a hole for me, but it really cut down the time to find a hole.
This winter I'm running Specialized Armadillo (Kevlar reinforced) tires with tire liners and thorn-resistant slime-filled tubes. Even so, I had one flat from a screw that pierced them all.
Glad you were able to find the source of your flat. That small a wire might not have shown up even with running your hand around the inside of the tire.