OK to ride with a slightly bent mech hanger? My rear derailleur took a knock from a fall, and the entire shifting range moved inwards by about one sprocket width. I suspect, but am not sure, that the mech hanger got slightly bent (could be completely wrong, not really sure how to tell).

I was able to counteract this by adjusting the limit screws, and the derailleur seems to be shifting well over the entire range. The way it's set up currently I can no longer push it into the spokes by hand (i.e. it's the limit screw and not cable tension that stops it).

I am tempted to just leave things are they are.

Is it OK to ride like this, or are there compelling reasons (safety, long-term reliability, etc) to figure out what got damaged and repair/replace it?

Here are some pics:
Derailleur hangers are supposed to be, to some degree, a component that bends to save the derailleur. The hanger on one of my bikes seems to get bent at the slightest impact. I'm considering ordering a spare and carrying it around in my tool kit.

If the indexing was severely affected by the fall (moving inboard a whole sprocket definitely counts as 'severe'), you need to address the problem properly. A bent hanger is going to affect shifting and put extra strain on the chain, and you risk the cage hitting the spokes when changing to the largest sprocket.

You can eyeball the derailleur cage alignment by looking down the chain-line from the back of the bike - see image below from this question. The derailleur cage should appear to be parallel to the chainrings.

My LBS only charges $20 for hanger alignment and indexing adjustment (I'm in the USA). Worth it to get the hanger straight and avoid associated problems.