Most any of the bikes like the softail, FXR and sporties where the tank is higher than the engine will do that after sitting a while. Usually if it continues some work on the bypass valve in the oil pump is needed on most bikes.
Try some marvel mystery oil available at auto stores in the engine oil without overfilling it and that may clean out the passages and return it to normal again after running it a bit.
Try some marvel mystery oil available at auto stores in the engine oil without overfilling it and that may clean out the passages and return it to normal again after running it a bit.