Generally, and does not rule out a cardivascular problem but an increased resting heart rate often remains after a new and markedly demanding exercise regimen is first begun. Sometimes it is due to some residual dehydration (you must be certain to keep yourself hydrated, by drinking plenty of water before, during and after these workouts); it also can sometimes be an autonomic reflex triggered by the stress of the new exercise.
Hope this helps, and monitor your heart rate as you continue to exercise!
i been having the same problem when i work out. im worried now.