The remedy for your problem is a fluid/filter change.
Best would be to have the fluid replaced first without the filter. Only about 60-70% of the fluid can be drained each time due to the torque converter containing the rest. After the first time fluid change drive about 2000 miles, then have the fluid, filter and gasket replaced as a complete set.
Make sure also to clean the magnet on the gear box pan.
The dealer ship will tell you that the fluid doesn't need replacement due to application of life time oil. disregard the advice and replace the fluids.