Hmm. I also see some strange things that have never seen before.
Lets take transaction
https://blockchain.info/tx/4af1a19fd6940758e2c4a3e779cb25023d93668c75a313f93e8008c0b075488eit was created ant sent a ~week ago with 0 fees and very-very low priority (date on bc.i is incorrect - tx is older)
No miner wanted to include this transaction into a block.
There was no reason to include this transactionYesterday somebody re-broadcasted it (bc.i forgot the first copy) again
Yesterday I redeemed it with
https://blockchain.info/tx/8a1f0f07fb397b2aa0e77995723f2dac9aee7df63a6f05a7db7d168d62a60f94with a fee of 0.0001
So, there is a reason now for a miner to include both transactions - miner gains 0.0001 (which is more than default 0.00001 per kb)
And these two transactions were mined! Of course, in same block (309837) because miner would not include first transaction without second.
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Update 1: No. Block 309837 contains a lot of free transactions.
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Update 2: child-pays-for-parent?