The chances of that happening is just like.... wow!
Not that unlikely actually.
Assume you have a 1% (1/100) chance every minute to grab a block because
you hold 1% of the network's total hash rate.
Then every minute you have a 1/10000 chance to grab two consecutive blocks.
So it takes 10000 minutes on average until you grab two in a row - about a week.
And a 1/1000000 chance to grab three consecutive block. That's going to happen
about once every two years.
But I'd rather win a lottery that really pays big.
Christian