xkcd

Many million years is nothing in geological or astronomical timescales. Any (small) body with a heat source that short is dead cold by know. The solar system is 4.6 billion years old and the formation of planets or larger bodys has ended about 4 billion years ago.

And tidal forces mean that a way larger body is close by, like a gas giant, as far as I remember are all known body's with tidal heating moons not planets.