When I looked at the cockpit this morning I noticed there was brake fluid on the floor. I had left the parking brake on for several days and it looks like pressure caused the line to disconnect at the firewall connection. It appears the line was not inserted far enough into the ferrel before I tightened the nut. I replaced the existing ferrel with a new one, inserted the line more securely and re torqued the nut. For good measure, I replaced the ferrel on the other firewall connection also. After refilling the brake lines it appears to be holding the pressure with the parking brake on.