ABS Issue - '95 LWB

Every once in a while with no pattern I've been able to identify, the ABS will kick in (activate) when coming to a normal stop on dry surfaces. Pulses/buzzes as one would expect it to if on slippery surface, etc. Warning lights for ABS and TC come on after that, but reset once car is restarted. It stops fine otherwise. My wife has said it happens once a week for her, happened to me for the first time on Friday night. Pump turns off after 30 seconds, no other warning lights, nothing else seems amiss... Ideas? Thanks!