Tonight after washing the TSX (it was about 50F here in MA) I decided I'd continue by cleaning up the engine compartment a bit. Anyway while I was using a rag to wipe down some of the surfaces in the engine compartment, I caught it on a blue knob by accident. The knob is apparently the Low Pressure Service Valve for the A/C. Since I'm not sure what position it is supposed to be in, and I'm not really sure how much I accidentally turned it, my question for anyone who can answer is, is this valve supposed to be completely closed? I turned it a little and heard a slight hiss that lasted about 1/4 sec. I turned it right so that it feels like it is closed tight, and to me this seems right seeing as its a service valve and would maybe be used to inject/remove the refrigerent? Can anyone help me out here? Thanks in advance.

That's exactly what it is. The spin off caps are an addition to the shrader valve, to help keep refrigerant in. Just make sure the cap is secure by turning it till it's tight, not elbow grease tight, just so that the cap is securly on there to prevent any leaks.