Irregular heartbeat Q?

So this morning I was relaxing on the couch when my heart began to beat really fast & with no particular pattern. It also felt like my breath was a bit delayed.
Here is a sample of my heart rate:
120 bpmish
Bbbb_B_BbbbBBbbbBbbbBbbb_Bbbb B B Bbbb
B=big pound/beat
b=mini-beats

Eventually, the pattern became regulated & about 30 minutes later was on perfect time again.
1) I wasn't stressed out, just relaxing...actually falling asleep
2) It has happened before, but randomly...usually when I am laying down.

Any thoughts?

Does this happen to everyone from time to time?

Add-
1) I am not on any meds/drugs
2) My bp, which I checked about 30 minutes later, was 118/78.
3) I am in decent health-excercise a couple times a weak, not overweight.

At 120 bpm if it was totally irregular without any pattern it could be an arrhythmia called atrial fibrillation. Arrhythmias are notoriously difficult to diagnose without an electrocardiogram recording however. When your heart beats very rapidly it is not pumping as efficiently and that might account for your shortness of breath. Generally speaking these types of arrnhthmias are not a threat to life but do need to be evaluated, and depending on the type may warrant treatment. They also can be paroxysmal and unpredictable and it is possible it may not occur again but if it does get a checkup. If you are due for your annual checkup anyway it might not be a bad idea to move that up just as a precaution.

Sorry I have no answer, I just love your avitar!!! I love the movie TOMBSTONE!! I'll be your huckleberry!!!

See a DR!!

The only time mine raced to 172 was when I had sudafed 3 yrs ago. It had pseudo ephedrine in it. I was OK after it wore off. That was scary!

I have low blood sugar, and if I eat too many carbs, my heart will act up with racing and palpitations. So then I eat more protein, and again have to wait until my system levels out. Since I figured out what was doing this, I keep more calm and don't panic.