The label reads, "Keep refrigerated after use."

I do not like cold mustard and find it inpracticle to heat that little bit of mustard. So I will ask:

How long can I keep the mustard unrefrigerated until it goes bad?

Hi Anticuchos,
Here is one recommendation:

http://www.medicinenet.com/script/main/art.asp?articlekey=54706

I really wouldn't know myself, though I think, owing to the relatively high acidity from the vinegar found in pretty much all mustards, it would be fairly resistant to spoilage for a time.
Hope this is of some help. Take care. :)

The label reads, "Keep refrigerated after use."

I do not like cold mustard and find it inpracticle to heat that little bit of mustard. So I will ask:

How long can I keep the mustard unrefrigerated until it goes bad?
I almost never keep my mustard in the fridge, for the same reasons you've stated, the worse that's ever happened is... separation, which causes "mustard water", basically, if you shake it, it blends back. But I also generally replace the bottle every couple of months. There's really nothing in mustard, generally but distilled vinegar, water, the mustard seed and various spices, like salt, paprika, tumeric and the companies secret "spices", so I've never had a problem myself.

"Spices" on anything typically means MSG, to enhance flavor. A dirty little trade secret. :)