odd/stray green atom

I love the Molecules app. Pi Cubed is even nicer.
I have found a bug however.

A stray, unattached, inappropriate green atom Chlorine?) is appearing at times.

I am seeing 1 in the following molecules so far.
- 1 near one of the nitro groups in Octanitrocubane (Pub Chem #11762357)
- 1 near one of the nitro groups in Heptanitrocubane (Pub Chem #11732527)

There's also one that appears and disappears at some distance, and detached from the main molecule, when I pan/rotate around in the Octanitrocubane.

See screenshots at:
http://www.flickr.com/photos/55526376@N08/5794211584
http://www.flickr.com/photos/55526376@N08/5794197464

-Eric