So a number ending in 'x' is as likely to be followed by 'y' as a number ending in 'n-x' is to be preceded by a number ending in 'n-y' (where n is the base).
Can't think of a trivial reason why that would be the case, something weird is happening.
Framing this differently, a prime congruent to x mod b is as likely to be followed by a prime congruent to y mod b as a prime congruent to -y mod b is to be followed by one congruent to -x mod b.
Can't think of a trivial reason why that would be the case, something weird is happening.