Just had 6 blocks within 16 minutes (ending ~17 minutes ago)
305463 17 minutes 395 2,273.73 BTC 72.83.147.125 243.36
305462 22 minutes 32 504.36 BTC Polmine 14.85
305461 26 minutes 81 497.38 BTC Slush 46.14
305460 27 minutes 35 469.12 BTC GHash.IO 21.07
305459 24 minutes 432 46,996.86 BTC BTC Guild 287.12
305458 33 minutes 128 101,239.74 BTC Polmine 148.88
Obviously a few fast blocks is just from
random odds.
6 blocks in 10 minutes has happened a few times before, just like 0 blocks in 60 minutes happens about once a month. 6 in 10 minutes is a bit rarer though.
Since DeathandTaxes did the math for the frequency of the OPs post, I couldn't help but do the comparison of this during one of my breaks at work. Hehe.
With ideal block propagation averages:
6 blocks in 10 minutes (i.e. P[X=6] for λ=1) once every ~13.6 days.
0 blocks in 60 minutes (i.e. P[X=0] for λ=6) once every ~16.8 days.
As a note the chances of 6 or more blocks in 10 minutes (i.e. 1-P[X<6] for λ=1) is once every ~11.6 days.
So it seems that 6 blocks in 10 minutes is a bit more common than no blocks in the expected time for 6 blocks.
So it is normal over twice (or even three times) a month?
Seeing the math is amazing thank you and DeathandTaxes for doing that.