Hi Eric
Those pics do look very similar to my modded camera which has clear ar coated glass so I am thinking some IR light is sneaking in past the 1100 nm area where the filter starts passing IR agin.
One final test is to take a picture of an electric stove element thats heated up to almost but not quite red hot. With my camera if I take such a pic the element glows strongly even though to the eye its still not red hot.
Hutech also have screw on versions of the VLC filter that balances it for normal daylight imaging, in 58mm, 67mm, and 77mm diameters but the one that goes behind the lens would be better if you plan to use other lenses, other advantage is it prevents dust getting in when changing lenses.
I use a screw on UBIR filter
http://www.sciencecenter.net/hutech/idas/uibar.jpg
It too lets in some IR past 1100 nm, I should test it with the stove element imaging . I only use it when astro imaging to stop excess IR light, it may stop most, but not all of it.
Scott