Infinity brake question

I have a 1999 infinity I30 with 105,000 miles on it and sometimes when you apply the brakes it is like you're driving on a washboard road. It may do it several times in a row and then not do it again for a day or so. I think it has something to do with the anti-lock brakes. I'm sure when I take it to the mechanic it won't do it. My questions is should I wait till it gets more consitent are take on now.
thanks
Buford