Did you place the back of the watch on your chest (in the V2 lead position) and then touch the crown with your finger to get this? If so, then the inverted T wave you are concerned about would not be a valid finding. The voltages in the precordial (V) leads in a 12 lead EKG are measured in relation to the average of the 4 limb leads, not just one arm which the watch is doing. EKG tracings from Apple Watches are good for determining heart rhythms but not much else.
Thank you so much for the education :)