Why does this happen? Without an underlying reason it's hard to believe it's any more than normal variance. To suggest that people who see it should follow it in later races is straying into the irrational realm of conditional probability.
If the propeller heads here think it's a 'thing' then it probably is, but it would be nice to have an idea of what supporting evidence to look for apart from there being six reds or six blacks in a row.
(quite happy for this to be bumped into it's own topic, I suspect it's not an easy answer)