I have ecg conclusion all normal except for iii avf abnormal t wave. what is this? should i take cautions? tks

May be minor: This is a visual test so can't say without seeing it. Why not discuss with the doc who has the test? T wave changes have many causes but some are very minor or even variations of normal.

T wave abnormality: If you have t wave abnormality in lead iii and avf, it may or may not mean anything. First, what kind of abnormality is this? This is, by far, the most important question. Most of such abnormalities are indeed benign, but it would be nice to know why ECG was done and what symptoms you're experiencing as well.

Abnormal T waves : Are not a sign of cad. During an acute coronary syndrome, an ECG may show peak t waves follow by st changes. I do not have your ECG to evaluate but i suspect are normal changes for you. If you are having symptoms like CP with activities a stress test will offer more definite diagnosis.