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.
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
Don't be so sure: http://people.csail.mit.edu/fadel/wivi/