Given the normal ECG, I am suspicious about how the ECG was undertaken. If the leads are mixed up or incorrectly placed you can get issues. Did you have both ECGs at the same place? If so it might be worth asking your GP to repeat it and to show him the previous ECG.....
I would not be too concerned. The worry with these T waves is that you might have narrowing of your coronary arteries. Not that common at 35......That would result in an abnormal exercise ECG because when you exercise the heart needs more oxygen. If the arteries are narrowed they cant provide it so the ECG gets worse. Yours didnt
Cardiac CT is now the standard often used for undiagnosed chest pain as we can get a 3D picture of these blood vessels rather than an indirect report from an ECG. It is also cheaper than an MRI.