That is an interesting concept, it would mean that the photon is moving at the speed of light even when it is within the atom, and simply continues travelling at the same speed when it exits the atomic structure.
That idea then raises the question: How do the various photons that can be emitted by an atom, coexist in such a small volume and why do they not influence the external world?
Another question would be: What method within an atom can create a photon that travels at the speed of light, even though the method that creates it, travels at a slower than light speed?
One theory of light states that photons are slowed down when they travel through dense material such as glass, the idea is that a prism causes different frequencies of light to be slowed down at a different rate and that is the reason why the prism can separate different colours from a white light.
If photons can be slowed down, then can they also be accelerated?