Had heart ablation 15 yrs ago for psvts. While laying on couch, just had a brief flip flop feeling in heart and lightheaded. Should I be concerned?

Ablation. If you've had 15 good years after an ablation, i wouldn't worry about an occassional flip/flop unless its very frequent and lasts a few minutes or longer each time. You should discuss with the dr.(s) who know you and your situation. They will be able to make a more informed recommendation to you.