I have had cakes shrink and some fall. I've had more trouble with the electric oven than a gas oven.
I originally thought the leavening might be a tad old until you said it was light. If you didn't slam the oven door or have a heard of elephants in your kitchen, it is probably the nature of that recipe to puff up and then fall slightly below the edge of the pan before it is finished baking. I've seen it happen more in chocolate cakes than non-chocolate, but that is probably because I make more of the former than of the later. I often wondered why it happened, but I never asked.
The only thing I am absolutely sure of is the oven temperature must be accurate.