Post-surgical changes in the breast can initially change with time although rarely this pronounced. N.b. this process does not carry on indefinitely. If this scar was to change again, say,  after three years, it would be a red flag and full workup would be done.

I suspect the initial change in the scar has to do with fat necrosis relative to the surgery. 

As with most breast pathology, change with time helps you arrive at a diagnosis. Never miss the opportunity to look at previous studies or look at your tech sheet. The answer is often there.