Thanks Ethan, set output did help, much appreciate your pointer.
I just opened and closed (as duplicate) a bug for this same issue. Just posting the...
Mismatched XML tag </g>
Duplicate of: https://sourceforge.net/p/gnuplot/bugs/1298/
Oops... didn't do a good job at searching. Found an existing bug report #1298 that...
Mismatched XML tag </g>