Did my first 'walk of shame' today - luckily it was only about 0.5mi away from my destination. Started noticing a bit more resistance than normal, very slight (headwind + slight incline I figured) - then after starting off from a light, I felt a LOT more bumps than I thought, took my left turn off Danforth (major arterial) and felt it squirm all over the place - thankfully the turn I took was very gentle, it was already down to about 30psi I'd guess. I felt it, carried on for another metre or so, decided it was way too low to ride on and walked. I just got back in so now's my time to figure out what happened.
Other than that, great ride - lots of bikes to chase/pass and also chase/try to pace with

One guy on an old Peugoet was keeping a really great pace across the bloor viaduct (Prince Edward viaduct?) and then we were both caught at a light by a guy on a Specialized Allez - I almost caught the Allez up but just as I was within a few hundred yards I hit the wall and then experienced the mechanical.
Overall a good ride though, thankfully it was lovely and warm out, made the walk not so shameful