Brief palps are common and usually no problem, but check with your cardiologist to make sure! Most of us have them and just don't notice. We start paying attention more after Nissen.
Palps can come from foods, as pegster noted, with or without intolerances, irritating the esophagus and triggering the vagus nerve. If they last long at all (check with your doc on this) and you can't get them stopped with Valsalva maneuvers, you need to go to the ER.
Valsalva is just holding your breath and pushing with your abdomen like on the commode. Coughing helps too. Your doctor may want you to chew an aspirin and/or take a Beta blocker like atenolol. Do see a cardiologist! I had a heart attack once when I had an esophagus-triggered coronary artery spasm (had high cholesterol and deposits in coronary arteries too). Another time I couldn't get tachycardia stoped for 5 hours, and ER had to give me adenosine (briefly stops the heart) to convert to normal rhythm. Not something you do at home!
When Nissen is done a lot of branches of the vagus nerve are cut along with a bunch of blood vessels (for which you now have hemo clips in your chest). I don't know if this has anything to do with the price of beans, but it is the same main nerve that connects just about
everything in you - heart, stomach, etc.