AddComponent calls "start" method sometimes?

I'm having a code that looks like this:

 void Update() {
    if (some_condition) {
       some_gameobject.AddComponent("SomeComponent");
       some_gameobject.GetComponent("SomeComponent").variable = value;
    }
 }

And then in SomeComponent I use variable in the start method:

 void Start() {
     Debug.log(this.variable);
 }

The problem I am seeing is that sometimes this.variable has a null value (and it shouldn't be). Is there any chance that the component's start method gets called before the line after addComponent is executed (where variable is initialized)? Please note that this happens pretty rarely (I had to bang my character's head to a wall a lot to reproduce the issue) which make this look like a race issue.