2006 GLS V6 - Noisy Lifters?

Recent purchase with 39,990 mi. Car now makes a very loud grinding noise when engine is turned over. It last a few seconds then goes away. If I turn the car off and let it sit a few minutes it does it again. This happens every time the car is started from cold no matter the weather. I took it in for service and was told that all of these cars make that noise. Is this true? Seems very unusual. They timed it and said it only happens for 4 seconds and that was within the appropriate range. Is this normal for these cars?

I have a 2007 V6 and it does not groan, take the car to a different dealer.