Mark is absolutely correct. Hormonal imbalance such as excessive thyroid hormone, or rarely, "adrenalin" can cause an elevated resting heart rate. Also remember that anything that enhances the normal release of adrenalin from the adrenal glands can also increase the resting heart rate: anxiety, fright, flight, stress, anger, etc. Don't forget the common stimulants such as caffeine and nicotine. Less commonly are low red blood cell count, states of dehydration and fever/infection. There is more to the list but much less common in a younger person. Worth checking with your doc if it persists.
Cheers, Canadoc