alcjphil has a good point. I"m guessing that probably most of those spokes on that side have the same issue. If it were me, I wouldn't panic. I'd just get a handful of those nipples, carry three, a spoke wrench and make a nipple started from a matching spoke. (To make a nipple starter, cut a spoke in half. Screw a nipple on backwards all the way and tighten with a spoke wrench. Now you will see just enough threads showing to start a new nipple at its top. Bend a nice handle into the cut end of the spoke. Now you can easily drop a new nipple into the spoke hole and hold it steady while you start it on the old spoke. (If your rim is an older, single wall rim, ie no hollow area to lose spokes in, forget the nipple starter.)

Now, mark any spokes you change nipples on and replace them at your convenience with longer spokes.

Nipples for too short spokes will break, one by one. But the point where this starts happening a lot may be many thousands of miles away. Ultimately, the wheel will want a rebuild with spokes probably 2mm longer, but that is nearly the work of building a wheel from scratch, so why sweat it until it's an issue? (Unless you are about to go on a venture where reliable wheels are required or spoke breakage is unacceptable. Touring, racing ...) Now it is also possible that this is the only short spoke (the builder ran short of the right ones). Good spokes will come to the tops of the nipples or a little beyond (on double walled rims; extended spokes puncture tubes in single wall rims).

Ben