You may not notice it from the "outside" but your aging rubber hoses can swell on the "inside". This allows fluid, under the pressure of your foot on the master cylinder, to flow out to your brakes but it won't flow back as quickly... causing your brakes to stick.
Bleeding regularly (once per year for a street car, once per event for a track car) will help keep them like new. Replace your factory rubber lines every 10 years.
**Images are for representational purposes only. Actual product may vary.**