Meh, lead free solder sucks.
Yes, it does. However, he was talking about cooking lunch along with his latest batch of PCBs, so...

problem you'll never have an issue because you're aware of it.
I'm a software guy, really... and I'm afraid that's something of an occupational hazard... if I don't think of every possible result and write code to guard against it, sooner or later it will come back to bite me.

Come'on guys... who plugs machine/digitizing probes into their laptop or phones.
Somebody who shouldn't have been messing with it... but was anyway.

I don't know who goes thru your shop, but if you ever get a new hire, and for whatever reason the probe isn't working, they might think "well, perhaps it needs to be charged". Or perhaps they are just curious to see what it enumerates as when plugged into a laptop. Personally, I've never actually seen a USB port "in the wild" (so to speak) that wasn't either a charging port or a data port (and often, both)... so having one on there might well set up an unfortunate expectation in someone who doesn't know any better.

Eh... I figure it's like carrying an umbrella... every time I take one, it never rains... but every time say "forget it" and leave it behind, I get soaked...

A standard USB uses pin 1 for power (+5v) and pin 5 for ground.
FWIW, Mini & Micro USB - yes. Old fashioned A & B are only 4 pins. (yes, I know that you know that, but I'm just making it clear to anybody else who reads this).

Crimeny... I'm getting old. I just called USB "old fashioned"... and I clearly remember when it first came out.