CGAL - clock screw when making?

I'm sick and tired of manually executing one command after another just to compile a darn c++11 program that makes use of CGAL.

So I thought I'd create a small .sh file that would take care of it for me:

#!/bin/bash

cgal_create_cmake_script &&
cmake . &&
echo "set(CMAKE_CXX_FLAGS \"${CMAKE_CXX_FLAGS} -std=c++11\")" >> CMakeList.txt &&
make

I don't really know much about bash scripts, but this seems to work well enough. However, I'm constantly getting warnings that

make: Warning: File 'Makefile' has modification time 2.4 s in the future

make[1]: Warning: File 'CMakeFiles/Makefile2' has modification time 2.4 s in the future

make[2]: Warning: File 'CMakeFiles/my_dir.dir/progress.make' has modification time 2.4 s in the future

Now, as much as I'd like a computer capable of predicting the future, I'm not really happy about this. What am I doing wrong?