actually it is still on ios 10. haha. and i won't upgrade the iOS. haha.

Haha, smart move, just like your Mini 2.

iOS 11 is the killer. If you had upgraded to iOS 11 then you would have no choice but to go to 12.

saw the performance 100%.. i think some apps running in background..coz it got heated some time..

Does the phone gets hotter (when background apps running) than when its charging? Heat is energy, the more more it produces the more energy it gives out. There would be some cause for concern. Some apps do make the hp hotter than usual, those high intense graphic games are such examples, non-the less if it runs hot even in standby mode, it should be checked by a technician ASAP IMO.

i notice if im using potret camera i can feel its getting hot.. is that normal for using camera potret..

Emmm, on mine, I only feel phone getting warm when I play high grapics games, on the phone on long periods, surfing the net (YT especially) for long durations. Short durations, like normal. BTW I am using Spigen Crystal hybrid case. I do use camera, but I have yet to encounter it to be running hotter than the norm.

hopefully got no defect one.. but stil got warranty can claim 1 to 1 right?

Best get it checked by authorised service centre ASAP bro, it may be nothing but to be safe.

ya need to check with service center..

Be prepared though, if there is any problem, it will take a long time to be ready and you will have to leave the phone there.

zzz they nothing happened. all goin smooth like charm.. now just us as it is..