I bought a pre-owned Carrera and after wearing it a few days, I noticed that it was almost a minute slower than my iPhone. I synchronized my iPhone stopwatch with the second hand on the Carrera and found that it's losing about 15 seconds or so over the last 24 hours. Is this worth being concerned and taking it to get adjusted it is it fairly common to have to reset the watch every few days? This is my first mechanical watch. I don't know the history or if it was on a winder or if it was sitting idle before I got it. Should I keep wearing it to make sure it's fully wound then check again?