Highly unlikely and ecgs are meant to be used with the full clinical picture, not just by themselves. The automated analysis on ECG are especially bad and has really high false positive rates.
But if you are worried, I would see a cardiologist to get an echo. Echo can show if your heart is not pumping well which could be a sign of a previous heart attack. If the echo is perfectly normal I wouldn't worry too much more at your low risk level.
Cardiac MRI is great for looking for scarring which is an objective evidence of previous heart attack. But It is expensive and in your case your risk is so low that it is not an appropriate test at the moment.
It is not likely about that, how about lead III EKG for you? In order to test you with past heart attack, you need to take cardiac MR or cardiac ECT. Maybe it is not necessary for you!
Not likely, go see the cardiologist and I'm guessing he'll have a different take on the EKG. In any case at least you'll know for sure..