No. Sinus bradycardia may just mean that your heart rate is slightly below the calculated and established "average hr" for the population. Now, if your hr is so low that it is causing symptoms, is not able to maintain adequate blood pressure and / or does not rise with increasing activity, then it is abnormal and you need to be evaluated.
Not necessarily. There are superbly conditioned athletes whose resting heart rates are inordinately low, but these are a rather select group of people. For most others, a good cardiologist will find out what is wrong.