Presidents commonly rely on autopens to sign their correspondence. As stated here:
"When Barack Obama takes up residence in the White House, Autopens, and to a lesser degree, secretarial signatures (signatures signed by secretaries or other assistants) will fill the vast majority of autograph requests."
"Since President John F. Kennedy, presidents and politicians have relied on the Autopen. Kennedy himself was reported to have had six different Autopen signatures. The best way to detect one is to compare it against known Autopens. Autopen signatures from the same template will be virtually identical. If you superimpose one image over another, the signatures will align almost precisely."
A polite letter of congratulations is exactly the type that should be expected to be signed by autopen. So the fact that the signatures appear traced is just as easily testimony to their authenticity.
Autopens have no hesitancy in moving from point to point and are incredibly precise. Nothing about this tracing was "automatic," precise, or even pretty. A forgery is easily a testimony to fraud: which is soemthing Obama cannot hide.