Ok, here is the story. I have checked the coolant levels today and i noticed a slight decrease in coolant level, 2 lines below F(full). In the 2 years i have the car this is the first time i noticed a decrease in coolant. I flashed the radiator 9 months ago and since then it was ok till when i checked today. Yesterday i removed the air pump and installed a DP,MP but i think this has nothing to do with coolant. No smoke from the exhaust, no sweet smell.

Do you think there is something i should worry about?

 

Not from your overflow catch tank. Levels will vary in the overflow tank due to differing circumstances. It's when you see coolant levels dropping in the filler neck (usually resulting in the low coolant buzzer going off) that you should start worrying.