For the current? Well, yes, I guess it goes to show the importance of converging in this number, a point perhaps not made strongly enough in our tutorials or manuals.
The underlying reason is basically that the transmission is a resonance, so if the electrode band structure has several local minima/maxima in the energy range, then at any given bias the overlap between left/right states is almost random. Notably, you don't have to converge the whole transmission though, just the relevant range which is intergrated for the current. Often the band structure and hence transmission is more complex farther from the Fermi level, but this makes no difference for the current at low bias at least.
