Why? Is there a problem? Are you worried that your code is taking 1 millisecond longer to execute in this case?
My point is, this is a suggestion that this code is not as efficient as it might be. It is NOT an error message. Just a suggestion to improve your code. There are some codes where the time would be significant. But for moderately small values of numb, you have now spent far more time worrying about the message than you will use in CPU time.
The solution is to use zeros to create the vector S, BEFORE THE LOOP. Use zeros. You know what the final size of S will be. Something like: