26 years old. new mole on neck. it's very small and kind of looks like a line. could this be cancerous? i"m hardly ever in the sun...

Probably nothing: Moles or nevi begin in the form of a small circular or nodular lesion, not linear. In order to define that lesion which converts or transforms to melanoma, one uses the Beslow classification of thickness of the lesion. Anything less than 0.75 mm and without a variegated pattern of pigmentation should be followed. Should the lesion enlarge, show signs of peripheral inflammation then do bx.