Recurring car sounds

We had our left axle replaced by Johnson's Automotive at the beginning of the summer because the van was making a clicking sound when turning. Almost right after that, we started hearing another sound when turning the wheel, kind of like a squeaky fast clicking. We took it back to Johnson's, thinking it had to do with the axle again, but alas, the sound stopped the day I brought it in. I explained the sound to the mechanic, and he suggested that it might be squeaky bearings in need of lubrication and that when we hear the sound we could bring it right over anytime. OK, great.

But now, it's as if our van is taunting us. The sound comes and goes, only occurring on weekends, or other times when we cannot possibly take it right over to the automotive shop. So we haven't been able to get a positive answer yet. I figure that since the sound is only occasional, it must not be too critical. It does get annoying, though.