Wondering if this is normal? Day two with the 45-200mm. Sitting inside playing back some of the test images I hear a sound. A little concern. Thought it's the GF-1. Switched lens. No sound with the 14-45mm. Remounted the 45-200mm. It's the lens. Sounds bit like a faint cooling fan. Started taking some images. Inside a dead quiet house I hear the focusing drive. The sound is constant, but a different frequency when focusing. Normal?