Strange Behavior of std::set and < Operator Overloading?

I understand that if the < operator is overloaded in C++ (for example, to insert custom structs into std::set), the implementation must be a strict weak order over the underlying type.

Consider the following struct and implementation. This implementation is not a strict weak order, but appears to work just fine on my machine without throwing an error:

#include <iostream>
#include <set>
using namespace std;

struct Pixel {
    int x;
    int y;
};

bool operator < (Pixel lhs, Pixel rhs){
    return lhs.x < rhs.x || lhs.y < rhs.y;
};

int main(){
    set<Pixel> mySet;

    Pixel *newPixelA = new Pixel;
    newPixelA->x = 1;
    newPixelA->y = 3;

    Pixel *newPixelB = new Pixel;
    newPixelB->x = 4;
    newPixelB->y = 2;

    mySet.insert(*newPixelA);
    mySet.insert(*newPixelB);

}

Is this the expected behavior?