Mamiya 645 aperture blades issue

Hi, I was just randomly gazing at my lens and then found out my blades weren't moving even with a correct attachment on the camera. I was switching between the A and M settings as well to make sure that wasn't it. This might be a stupid question sorry. Also, I figured that out after a cold day of shooting (30 degrees f). Thanks.

Generic answer, it's in need of a cleaning.