3 days late, copper IUD

So it turns out I'm 3 days late...normally my periods are really quite regular (however last for ages, with loads of spotting before and after) and this time I'm late. Not sure whether I should be worried or not? I haven't got any sort of symptoms at all, so is it my body just settling down, or is it more likely be to the fact I've started back playing sport / exercising etc, as well as having quite a bit of stress/anxiety about my BF working in Africa for 3 months??