I had that problem about a year ago. I noticed it off and on for a week or two, and then it quit. I haven't noticed it at all this winter. Maybe my nose just doesn't work anymoe.

95 Contour Zetec, ATX (wrecked, sitting in the barn) 95 Mystique Zetec, MTX 2000 Taurus SEL 3.0L Duratec 1994 Crown Victoria LX 4.6 V8 1993 Chevy Silverado 4.3 V6