1992 Honda Passport ABS?

In May 2008, I had new brakes, front and rear installed by a trusted mechanic. Weather has been dry, so it was weeks before I drove it after a heavy rain. Then, I was going down a small hill at about 15 miles an hour. Started applying the brakes, car began to slow down normally. No sliding, no fishtailing. Then, suddenly, there was a loud noise like rocks crunching against metal and the wheels just kept rolling. Again, no sliding or locked wheels, they just kept rolling. I was approaching another car, so I cut to the right and the car finally stopped inches before I rear-ended the person in front of me. The rest of the way home, the brakes worked perfectly, so I thought maybe the brakes were just wet. They continued to work perfectly for three weeks until the next rain. At that time, I was approaching a traffic light on a flat street, slowing down to 20 mph or less, brakes working perfectly. Then, the rocks/metal crunching sound and the wheels kept rolling. This time, I had more distance between me and the car ahead, so I was eventually able to stop. That was 3 weeks ago and the brakes have worked perfectly since then, even in wet weather. No ABS light or any other other light. What's going on? Seems like the problem might be ABS since it only happens when the street is wet. Might something have been reinstalled incorrectly after the brake job?