Chocolate Colored Exhaust?

Hmmm OK, well this car has recently had a bout 200-300 mile on it (in the last 2-3 weeks). And the tune (carb/timing) had not been changed in over a month (by me). I just never have made a mental note of anything brownish like this before from an exhaust.

Just checked the plugs and there is a barely noticeable hint of oiling on cylinders 6 & 3, and a very, very mild indication of oiling on #5; it's just slightly shiny/oily on the outer metal body & threads, nowhere else. Nothing that would bother me except that the oil rings are not perfect anymore or the guides are loose; the rings may be sticky as this car had been driven an average of 130 miles per year since 1991. Compressions are (1 to 6) 115-110-120-115-120-115 psi (cold and not being started today before the test) so that seems pretty darned good.

One other variable just struck me and relates to the above 2 comments: it HAS been really humid and rainy here in the last 3 weeks, much moreso than is typical here in July; it has been more like Seattle here lately than the VA mountains in summer. Maybe the extra moisture is cleaning out carbon and effecting the color.