If you try to post twice in a short amount of time, the second post costs 10x.

So, posting in ~AskSN costs 100 sats normally, but your second post cost 10x that (1000 sats). If you had waited a few minutes, it would have dropped back to normal posting costs.

Here's some sats and I'd love to hear more about your novel project (although maybe wait a few minutes if you are going to make a post about it).

Also, comments don't cost 10x, only posts.