[98SubaruOutback]

I know that subaru's have a piston slap in the cold weather, and last week in the northeast was pretty brutal...however earlier this week it was in the 40's and 50's and when I started my car in the morning I still had slight piston slap...I let the car warm up for a bit and I still hear it but is it something I should be worried about? My 08 Outback has 86k on it now