Interesting. I have also experienced a similar problem involving a Knoll lens flare effect (v. 3.0) and obscuration, in this case some 3D text, backlit by a Knoll flare applied to a background layer. The flare moved across and behind the text and faded in and out either side of the text within the comp frame via keyframed opacity settings. The pinpoint of light appeared against the background at the end of the flare's path (beyond the text) on an opacity keyframe that was mistakenly adjusted to 1% instead of 0%. However after re-setting it to 0% and RAM previewing the pinpoint of light remained. Couldn't be eliminated. It was permanent and was also visible in the rendered output. The only quick way to eliminate it was to replace the background layer with a new one, add a new Knoll lens flare effect, copy and paste the keyframes from the original Knoll effect, check the opacity was indeed set to zero at the total fade-out frame and render/playback again. The pinpoint was gone. Puzzling. Not sure if this is what's happening in your case though.
It's a bug in their plug-in that has been there since god knows when...
Oh, ok... cool, thanks!