I have a CW C60 Trident Pro which I got around September last year. I keep it on a watch winder and I set it at the beginning of May (after the April date flick) and left it. Today I notice it is over 5 minutes slow... by my maths that's an average of -25s per day. I don't think that's within the acceptable boundary for a Sellita SW-200. Anyone any thoughts?