My wife has an 09 Rav4 V6 and it's not until I drove it recently that I noticed a vacuum/squeel noise that comes on when shutting the engine off. It only happens when shutting off the engine and would last a second or two. The noise doesnt happen any other time. Local Toyota dealer thinks it might be the pulleys. If that were the case wouldn't the noise be a little more persistent especially when the engine is actually running? Thoughts?