You definitely should. Maple necks can warp if it's exposed to changing climate conditions - which is just about always except in a climate controlled room... To avoid this, Warmoth specifies that necks made from certain would MUST be finished in order for the warranty to apply. Other woods won't warp and can be left unfinished. If the neck has to be finished, that would include the fingerboard if it's made of one of the woods that can warp. In other words, maple neck with maple fingerboard - the fb has to be finished, maple neck with rosewood board- the fingerboard should not be finished. On a different but related note, I think there's no concensus if Tru-Oil satisfies the 'must be finished' condition which goes on to state that 'oil finishes are not satisfatory'. From what I know, Tru-Oil is a hybrid oil - varnish finish and for me personally it's OK.