I think you got a bargain. You'll find it a really rewarding lens. I have one of the more recent Ai variants, which I think cost $69, then one of the f/2.8s came my way for $59. I've seen pre-Ai models in excellent condition going for $49. Such prices are just absurdly low for the quality and capabilities of these lenses. Nice photo of the salt-shaker too, by the way - I actually like the hexagonal blur highlights produced by the f/3.5. Bokeh is in the eye of the beholder ...
Cheers, John