Last night on Mad Men, why did Don call Peggy?

Question

I missed the part after the accident. How come Don called Peggy? How did that happen?

Answer 1

Because he needed to contact someone who would keep his secret ... later in the show it flashed back to Peggy in the hospital after having the baby and Don was there visiting. In a sense she owed him one and now they have to keep the other's secret.

I loved it when she broke down the barrier and called him by his first name.