OP here. It is a minor worry of mine. As pointed out in the comments, you could hotlink the trap and mass block many unsuspecting people.

That could be a problem for a major site - but I doubt your neighbours are going to miss reading my blog.

I'll probably set it up to remove IPs after a few weeks.

But, ultimately, I care more about my bandwidth than I do the collateral damage of a misidentified IP.