Although I'm sure this thread is getting a little old and has probably veered off course several times, I do worry and I went and had it looked at. Here are the results. I was told that there is really nothing to worry about and to keep up with the bike riding. The Dr. was rather impressed when I told him that 2 months ago I had ridden 450 miles, but that the current month was down around 250 miles.

HOLTER MONITOR FINDINGS:
1. This is a good quality 22-hour recording showing underlying sinus rhythm. Low minimum (43 bpm), average (61 bpm) and maximum (90 bpm) heart rates.Normal diurnal variation in heart rates.
2. There are rare (6) isolated, unifocal premature atrial contractions.
3. There are occasional (412) unifocal premature ventricular contractions. There are brief episodes of ventricular trigeminy. There is one ventricular couplet. Ventricular ectopy is primarily during daytime hours.
4. There is no significant bradycardia, pauses or conduction block.
5. The patient reports "heartbeat" (palpitations) several times in the diary which correspond to periods of increased premature ventricular contractions.