This could easily be resolved by setting it to resize 2 pixels instead of 1 and making it longer intervals, but that would make it more choppy
Your game or app should produce the same results regardless of the framerate. Some people will run it at 240 fps, others at 60 or maybe even 30. Then your "Every 1/120 seconds" condition won't work. If you want to resize the object properly with events, do it on every tick and make sure to use delta-time.
I would suggest using the Tween behavior instead - it's a lot easier. You just set the target size and time and it will resize the object properly. One added bonus is that you can choose a nice easing effect.