Today i found out i played 4 months out of the last 2 years dota 2. Meaning on average i have probably around 5 hours a day gaming overall . Other than that i'm doing ok. I have social life, i go to the gym (sometimes), good health, had girlfriends, got part time job while in university. I am not feeling addiction problems, unless i play all night (rare), but the amount shocked me. Should I be concerned? 

If you dont institute changes of habits, character, daily plans right now you are going to slumber on until it hits you hard.

bad habits take you out stealthily, without you noticing it.

Thank you for the warning i didnt think of it that way

Even if you don't feel like you have an addiction, there are two questions I would encourage you to ask yourself:

1) Can you actually stop gaming? If the answer is no, that is a serious indicator of an addiction.

2) 5 hours per day on a video game is a lot by any standard. Do you have other goals in life that might be more meaningful to you than playing games that much? You may not be addicted but spending that much time on video games might be stopping you from doing other things you really want to do.