Oh, sorry for my earlier post, I got myself messed up into cycles and radians, yes, the phase difference is pi.

Again, sorry for the confusion, I was initially thinking 1 cycle -> pi

You see, when you released the sphere from a maximum, you aren't forced to see it as a sine curve, but you can see it also as a cos curve, and from there, you see immediately that there is a half cycle difference between the first maximum and the second maximum, no need to find quarter of a cycle and add to another quarter of a cycle.