Puppet pin to follow another with a delay

Hi all.

My problem is probably really easy to solve, but I can't figure it out (I'm just starting with AE expressions).

I have a circle with two puppet pin points, ppp1 at the bottom and ppp2 at the top. 

What I want is ppp2 to follow ppp1 with a delay, but only in the x axis. 

I found this:
delayFrames = 4;

p = effect("Puppet").arap.mesh("Mesh 1").deform("Puppet Pin 1").position;

idx = parseInt(thisProperty.propertyGroup(1).name.split(" ")[2],10)-1;

delay = idx*framesToTime(delayFrames);

p.valueAtTime(time-delay)

And it works but with the x and y, and I want it only to follow the x, maintaining the y the same.
How can I do this?

Thanks in advance!