Electronic – Could 48V arc across this small gap

The photo is a bit too unfocused for me to say for sure, but it almost looks like there was an inclusion under the mask when the board was manufactured. I looks like a bit of air/dust/liquid in there "popped out" through the mask as you overheated the area while trying to re-work the solder bridges.

2 things I'm seeing from the underside shot:

1. The blister appears to be in an etched gap between copper traces, so as long as it didn't carbonize (thus potentially creating 1 or more shorts), it's likely that it won't severely impair function of the circuit (depending, of course on exactly what signals will be on the adjoining traces...high-frequency signals can be very temperamental when it comes to trace irregularities, but DC usually doesn't care much).
2. I think I see some heat damage to the vias/thru-holes near C79, C82 & a few of the other caps near the perimeter of your SMD as well. I'm guessing that there was a fairly significant amount of overheating involved, so a few of your components may have been damaged by exceeding their thermal tolerances (probably more likely than the PCB damage effecting performance even).

In the future, I'd recommend practicing with a few low-priced components on disposable PCBs, until you can get your temp/timing down on new soldering techniques...it has helped me avoid many costly mistakes, to be sure. Also, when you have bridges to fix, try letting the part/board cool for a while after the initial solder, before re-heating to fix the bridge. It's a technique that helps keep the heat from "sinking into" your components & causing damage...i.e. lets you have more time to work with a lower risk of damaging expensive components/PCBs. ;)