What does it mean when a mole goes from dark brown to tan, expanded a little to.

Most likely nothing: It is a good idea to have your doctor look at any changing skin lesion. Benign skin lesions can also grow and change. Generally speaking, if a mole is larger than say a pencil eraser (6mm), edges are not sharp and clear, scaling or bleeding, the pigmentation is not uniform or even throughout, or obviously changing you should have it checked. The doctor may biopsy the lesion if necessary.