oil on the filter

[snowmizer]

changed my oil the other day, noticed on bottom of filter that there was a big drip of oil on the bottom of oil filter. wiped it with my finger, oil was clean like new. climbed up top and noticed a tiny bit of clean oil in the overhang grooves of the filter. dont see how this could be because oil had about 3700 miles on last oil change. pulled filter , no double gasket{ left from previous change } and existing gasket perfect on filter taken off. any ideas ?