I think what happened was that the starter solenoid and starter relay got quite hot when you were sitting there. While you were in gear, with the clutch pulled in, there is slightly more drag than when in neutral. This combination can sometimes be just enough to stop it starting. After a few seconds without the fan blowing all that hot air (plus the heat from the exhaust) it cooled down a tad, and with the bike in neutral, it started.
Some of these bikes seem to start no matter what, others seem to always be on the brink of not starting, and there are a whole bunch somewhere between those extremes. I suspect it is due to a bit of tolerance creep in manufacture.
btw, I called Triumph USA a couple of years ago about the 87 or 89 octane required for the bikes. I was assured that 87 is fine, as long as the bike doesn't ping. The reason I called them was that the original spec was 89 but it was changed a few years after introduction to 87.