Coins minted, but did not split

Usually, when my Peercoins mint, the coins that did the staking are split into two equal amounts. However, during a mint that happened yesterday, the staking coins (about 1,005 coins) did not split into two. Is that normal?

Here is the transaction ID:

The output splits if it mints in <90 days, I believe. With this particular one, it looks like it minted in about 100 days (august 10th to november 22nd).

Thanks. That’s a security feature, isn’t it. Could you (or someone else) explain how that helps PPC security?

Pos security is maximized when minters stake with 90 day stake, so if you are minting shorter than that period it splits the stake up so that instead of minting once every 60 days, you now mint twice at 90 days each with half the stake (as a hypothetical example; numbers are just for show, not calculated). It benefits the minter directly because it increases the compounding interest (more and more frequent returns) and it benefits network security by moving your outputs closer to the hypothetical ideal stake size. There is no true ideal, as it changes with network conditions and random chance, but this mechanism is ‘close enough’ for all practical purposes.