I am asking a follow-up question to "Private" MAC Address.
Today I found a wireless device with the following MAC address on my home network:
Looking that up at http://aruljohn.com/mac/28EF01A9F10A says it's Private. The MAC address does not follow the second-least significant bit of the most significant byte set rule mentioned in the referred post.
On my network is an iPhone 5, a Samsung notebook running Windows and a Raspberry Pi. The Raspberry Pi is connected by wired LAN and is showing up correctly with its own MAC address.
What is the most likely explanation for this "private" device? It disappeared after about 10 minutes.