Andy and Tom,
I think this is one of those where manners must occasionally meet practicality. This subject just came up the other night, as it happens...
What Tom says is certainly true from the Emily Post perspective. Also, with very delicate glass, one can lift the bowl from the stem! I've the unfortunate experience of doing this, when young, with one of my Dad's 18th century venitians (no not california). He was nice about it but since I always lift from the stem. I imagine some of the Reidels could come apart like that too.
But, if the wine is too cold, a little hand warmth can really help. Like Andy I rarely remember to "chambrer," and in any case (as well known to afw regulars!) my house is very cold. So with our regular glasses we don't hesitate to cup them, and the wine appreciates it.
-E