Yeah, that will happen sometimes. But I don't think it matters weather you are loged in automaticly or not. It also depends on what forum you are on too. For example, Off Topic has a high rate of posts so a lot of times it can just take 5 or 10 min to make all the threads blue. But for some of the others that are not as active you will see the difference.
And welcome to the forums. 😀