I haven't put much thought into it, but I wonder why they don't randomize all probe requests...
[1]: https://www.apple.com/business/docs/iOS_Security_Guide.pdf
Your neighbour would be using some sort of correlation to work out the MAC anyway, so all they'll need is that it doesn't change over time for your access point.
Don't be so sure: http://people.csail.mit.edu/fadel/wivi/