Same thing happened to my fuel gauge (but luckily not the temp. gauge). I took out the cluster to fix my erratic/occasionally jumping tachometer (the screws holding it in place were loose) and while it was out I carefully moved all the needles to make sure they moved smoothly. Unfortunately I moved the fuel gauge needle just a bit too far, too close to the full mark and that can apparently ruin the fuel or temp. gauges. It says in the service manual that if you are checking the electrical connection at the fuel pump or at the temp. sensor that you have to stop shorting it (to make the needle move) before it reaches the full mark or it will damage the gauge. I was aware of that but didn't realize it would also apply to moving it by hand...

The tach. and speedo. needles can be moved by hand to check for binding [and I believe this applies to all the gauges on newer models (honda/acura at least), even the temp. and fuel. I believe for Civics it's the '01+ that don't have that quirk anymore] - although they shouldn't bind unless someone has messed with the cluster previously - but the fuel and temp. pod of all older Hondas/Acuras (and I'm sure many other makes) should be left alone when the cluster is being worked on as they're obviously very finicky.

edit: you'll need a new temp/fuel pod to fix it, and unfortunately those usually aren't sold separately that I've seen. I'm talking about ebay of course. Even then you can't be totally sure those temp/fuel gauges will work b/c people have reported that as an issue with used clusters off of ebay.
If you have a salvage yard close by that has your type of cluster you might be in luck.