If you look carefully you should see that the expanded bits, correspond to
where you overlapped your strokes, this overlap can become overwet quite
easily. They virtually always go back, they just take time, sometimes up to
36 Hours.
Don't worry about it, reassure the customer that it is expansion in the carpet backing,
and that it will go back to normal within 12 - 48 hours. If the worst comes to the worst,
get it stretched out, but i'd put money on it not being necessary.