I've been getting a racing heart / heart palpitations quite a bit. Often it's heaps in one afternoon, and then fine for the next few days. Not sure what it's about, but my midwife seemed totally unfazed and just said 'yeah, that's normal'. I guess it's only a major issue if you've got existing heart trouble or it's causing you stress or discomfort. No harm in checking with yr gp, ob. or midwife though.