I would get that checked. My '05 did the same thing and after 5 quarts of antifreeze to get home and a trip to the dealer, I found out that the head bolts had stretched and the heads were no longer sealing. The high pitched squeel was excess pressure in the cooling system. This also caused my truck to overheat when pulling my 13,000 lb. 5er. Watch your temp and get it in if you have problems.