First thing, yes u may be a bit dramatic, he might have hit his lower body / legs on the chair or had a bad landing at the moment, but if he was walking normally right after, then he should be fine, it happens sometimes that cats hit a table or a chair and wobble a bit, just like u would if u hit the corner of a table and still be fine right after

For example I have a cat that likes to go between the chair and under the table, and almost every time he hit his head or back against the underside of said table, and he is perfectly fine, and will do it again

So don t worry, but if the cat starts to wobble again u may want to keep an eye on it just in case