Anti-Lock Brake Issue

I think I've got something going on with the anti-lock brake system but I need some support from the group. While drivein this weekend on the freeway I heard what I believe to be a warning buzzer from behind the dash area on the drivers side. About 10 seconds in duration and then stopped. No indicator lights. It happend twice over a 400 mile trip. The only thing I can think of is the anti-lock system since I receive a very loud noise when the system engages as I move forward from a stop or after backing. Any ideas on this one? I have a 95 sl2, about 72k miles.

Antilock should only activate when the computer senses a wheel beginning to lock up. What kind of noise do you hear and where do you hear it from?