It is indeed likely that you are correct. We had trouble with the pumps on those machines during the first 3 years of production and the pump vendor was changed afterward to a different company. Replacing the pump now will get you the upgraded part. This can be a transient noise at times, frustrating someoone who is trying to diagnose the sound. After my stint at Maytag Customer service from '94 to '06, I saw a lot of transitional failures such as this. Unfortunately the consumer becomes the ultimate guinea pig.