It could be. I'm experiencing the same thing after 5 years. They're not full blown SVT episodes, but shorts runs as well as salvos of PAC's under heavy physical exertion. What you and I are experiencing isn't out of the ordinary. It CAN come back. In my case, a 65 y/o male, my cardiologist is wondering if it could be the start of A-fib. I've increased my Metoprolol to 150mg. per day and have a followup in mid July. It probably wouldn't hurt to check in with your cardiologist to let him know what's happening.
All that is done when they do an ablation is create scar tissue to block the signal from getting caught in a reentry circuit. In the case of younger people they have a higher likelihood of the body repairing itself so reoccurance is much more common. Also, if you have a small heart it is possible the EP didn't want to be too aggressive with the scar he created so as not to damage the heart. It's no use to help the person if they do more harm than good but in your case maybe they didn't do quite enough and some signal is sneaking around the edge of the scar. I know my EP stopped before the allotted time they suggest for scar creation so it is very probably the same happened for you. I would do as Tom suggested and make an appointment with the EP and let them know what you are experiencing. Get a monitor to catch it and see if it is indeed the svt coming back. A followup ablation from what I understand usually does the trick for good. Best of luck sorting it out. Keep us posted on how you are doing.
How are you feeling these days?