Question

Have the planets gotten any farther away from sun since the solar system was formed?

Answer 1

No.

Explanation:

As long as the sun's mass is stable its pull on each of the planets remains constant. For a planet's orbit to change in any fashion there would have to be a change in the sun's gravitational force, the planet's speed, or something of large mass crossing near the orbit of a planet.

As an aside, the moon is ever so slowly drifting away from the earth.