So i recently bought an 02 f4i. I've slowly doing all the maintenance. I just changed the rear brake pads and bled the system with a bleeder and all. While riding the next day i was going about 60 down the street while my bike started slowing down suddenly then to a complete stop. Turns out my rear brake somehow self pressurized. I couldn't pump it or get it to unstick until i released pressure through the bleeder valve which then freed it what can be causing this?