Inconsistent image conversion defaults?

I'm converting molecules into PNGs using the MolConvertWS SOAP interface.  I was using simple conversion parameters ('png:w200,h200') as the defaults suited my purposes. Today I came across a molecule that rendered in ball-and-stick 3D view by default (rendering explicitly with the 3D defaults creates the same image), while all the others I checked were still 2D wireframe. I switched to explicitly using the 2D defaults ('png:w200,h200,H_heteroterm,#ffffffff,cpk,wireframe') and it displays as expected now.  My problem is solved, but why did this molecule render in 3D by default?  This was the offender:

591753
  -OEChem-02060611583D

  7  6  0     0  0  0  0  0  0999 V2000
Ez-VGa3Wb10W60
hxyVEA+Va10W60
L00WN--VK00W70
8Y3W31+VVz-VG0
ir2WutwVjg+V80
Js5WEG0Wkg+V80
Nt4WOHzVef4WH0
10301
20301
30401
40502
40602
40701
M  END

I'm using JChem 5.3.4 and JChem Web Services 5.3.4.

Edit: spelling

Image export considers the molecule dimension (2D or 3D) to choose rendering mode unless it is specified explicitly. The default 2D rendering mode is wireframe meanwhile the default 3D rendering mode is ball and stick.

So, specify explicitly the rendering mode to standardize the rendering for all molecules.