It's definitely possible that your hands could warm the icing and make it a little more fluid - just as icing that comes to room temp from the fridge gets looser as it warms. I find that if I work with the same cone for a long while, the icing can get a wee bit looser, I presume from handling it a lot. Though I imagine it would only get more fluid up to a certain point, especially if the icing started at room temperature, and that the variations would not be very large. I say this, because your body temperature isn't nearly hot enough to liquefy sugar (melting point for granulated sugar is between 140C and 180C, depending on who you ask.)
Was the icing at room temperature before you started? That could have been part of the problem, if it was warming up as you worked. That all said, you could try doubling up the bag (so there's more insulation, in effect) or working in a cooler environment, as mrshugs suggested. And see if you notice any material difference.
When I'm doing chocolate work, which is much more sensitive to temperature variations, I usually want warmer hands - so the chocolate doesn't set too fast! So menopause isn't all bad! 