A ha! what I was seeing (according to the Heavens Above page) was the combined brilliance of both Mars AND Venus - which I guess might be why it was twinkling (light from Mars being refracted against the atmosphere of Venus?)

Planets in general are not supposed to twinkle. That's what fooled me. [img]/phpBB/images/smiles/icon_smile.gif[/img]

Sky from my house this morning:
http://www.heavens-above.com/skychar...on&BW=0&SZ=600