I guess it depends on what you're trying to gain by aging it. Are you trying to improve/change the flavor, or just trying to figure out how much time you've got to drink a batch while its in peak condition? Assuming its standard strength for a hefe and fermentation was well controlled, there's no need to age a hefe.
As far as improving the flavor, the lower alcohol means that there's a greater chance for an infection to pop up during the aging process. Plus, some of the flavors associated with aging of big beers are due to very slight oxidation, which while in a RIS might be enjoyable, in a hefe will probably stand out. I'm not sure whether or not the phenols/esters present in a hefe decrease over time, although I'd be inclined to think they might.
I've never heard of the hefe yeasts being inherently less stable, although I suppose it is possible, or maybe a by product of the fact that there's more yeast in general within a bottle. I know plenty of people use the same hefe yeasts to brew weisenbocks and these can be aged for long periods without problems, so I'd be surprised if rapid autolysis is something that hefe yeasts are prone to do. So I suppose its possible to age a hefe, although I'm not sure that there's a good reason to do so.