Have experienced several myself. Most common reasons for the go-around are traffic related, such as failure of the previous aircraft to clear the runway in time (either landing or taking off) or vehicular or construction traffic on the runway. From your description, it doesn't sound like a separation issue. In my experience, crew usually makes an announcement of some sort after they complete the go-around procedure. One time pilot came on and said he "didn't like the look of the vehicle that was on the runway." Another time was the failure of the previous aircraft that landed to clear the runway in time. Another time was much earlier in the approach due to too little separation with aircraft ahead of us in the pattern while landing during a snowstorm in Boston. In all cases, there was very little cause for concern.