Is it possible...

to see Just a hint of chocolate milk on the dipstick?
got over 500 miles on my '65 273 rebuild. Oil has stayed clean and full, mostly local short trips and a few short rips to show off a little.
I took my first distance trip today, drove it 50 miles to work and 50 miles back home in some rain on the way there. (alway's kept inside, and never drove in rain... whoops)
I checked the oil when I got home, still full and clean but what is that? a lil smear of light colored bubbly line down the side of the stick and just on the tip of the stick.
Wiped it off rechecked, same thing. Hmmmmn, It doesn't have Chocalate Milk Oil so, how can it have just some?