Hi Cris,
The actual GPIO speed should be 477KHz I measured this between 460KHz-444KHz, so there is a bit of a discrepancy between expected and actual timings.
In my case - the timing was measured at 38.4KHz (38.4KHz = 460KHz/12):
One of the main problems with the GPIO timings is they can be non-deterministic.
User SpiderKenny does a good job of describing why the GPIO timings are not very precise:
https://communities.intel.com/message/246733#246733
This could be what you're seeing here.