You have had it so long, I would not be concerned. Indeed if it lasts for a long period of time, sure get it checked out. People can have Tachy for hours and even days. 10 seconds is quite short, and especially since you have had to for so long, and only for very short periods.
Stress, Panic, Anxiety all will drive you heart rate through the roof.
Sound like your heart gets an old shot of Adrenaline for some reason and send you heart rate up.
I would not worry, enjoy your Xmas and new years and even when it does happen, think of it as your old friend paying you a visit once again.
The more you stress, the more you start to feel things, and the more you make them happen.
So don't Stress
I think you may feel a sensation, you Panic big time, feel your heart, like you have been frightened. This shoots adrenaline into your heart, like what happens when someone scares the hell out of you, and then 10 or so seconds later once your fright is calmed your heart slows again.
This is how I make my PVC's worse, I stand up or lie down, and think, "oh no this is going to cause them to happen again" low and behold I get stressed feel the pulse and BAM I start to get them.
My stupid head does me in all the time. Vicious circle