WiLLrOx

I lowered my car a little over a month ago and I noticed that when driving on the freeway I hear a squeaking noise coming from the right rear side. It only happens on the freeway though. The sound comes and goes and it's very hard to replicate. It doesn't happen when I go over bumps or imperfections in the road but it will happen when I'm going straight or on a turn. Any advice on what it could be? Could it be the shocks? Maybe an installation error? My car currently has about 43,000 miles.