CodeIgniter 3.1.4-3.1.5 HTTP Session issue

Hello Masters of CI.

TL;SR
(too long; should read) 

I have a small but interesting issue regardless of the versions of CI. 
Yesterday I downloaded v3.1.5, extracted and write a simple code ( https://www.tutorialspoint.com/codeignit...ncepts.htm ) then executed. What I paid attention that the browser still continued to wait for the code to be executed, as if the HTTP Session still continues, but the code is over and I see text that I need to see. I tried the same example with v3.1.4 but here everything worked OK!. The Question IS: Is this OK! or there is something wrong?

I am a beginner so I do not know how to go after the bug and hunt it.

Thank you in advance