Not so sure. Palpitations are often nothing serious, but what I heard is that not feeling your heart beat is normal. Except when you exercise hard. I feel my heart pumping when I lay in bed an my pulse is 60-70 bpm.
I've been told otherwise by a doctor (not a cardiologist), and I've always wanted to know a definitive answer on this but it's hard to find information on the subject; almost all literature is focused on the rate of heartbeat, not on the loudness of the drumming itself.