I'm not a geologist but we do have a similar spring on our land. This only appears in very wet seasons. The underlying soils at that point are a good, free draining one, which just where the spring pops up changes to a 'lentil' of glacial clay, which doesn't drain well at all. So it seems that water draining downhill from the free draining area, meets the less permeable clay, so runs over the top for a bit.
I think it won't be possible to suggest what may be causing your little spring without knowing the soil and underlying rock.