The moment you dropped tuning the neck moved. It will loose relief. It is either playable or it is not. If it is not, it will need to be set up for the new tuning. Usually a truss rod tweak will suffice. After that, the bass will be fine.
A neck is a balancing act between the tension of the strings and tension of the truss rod (relief). Once in balance, maximum playability is achieved. Weather temperature and humidity change that balance on a daily basis: The neck is always changing the balance even if you stay in standard tuning. Down tuning is merely another balance factor.