Well if you can do it for that long, there is nothing wrong with your body.
One thing that happens to some men over 35 if that the way their erections work changes. When you were 18 it went up at the slightest stimulation and stayed up for a long time, even if the stimulus was removed. As you get older, the erections tend to wilt faster when the stimulus is gone. But you can soon get hard again with renewed stimulus.
In the ESO book (extended sexual orgasm), the authors who are both doctors recommend an exercise for older men with your problem. They get their wives to stimulate them to erection manually. Then stop - wait for it to wilt... then start again, carrying on until erection returns. After several cycles of this, the man gets used to the fact that erections can easily be regained with fresh stimulation.
It makes little difference if the stimulation is physical or tactile. Which is why it helps to focus on sex when you are having it
The fact you are not cumming every time does not matter - the urge will build up and you will cum whenever your body wants to get rid of semen.
Re: Is this normal 
Again never had this problem till just over 2 weeks ago....
