It's definitely the scale - once I got them outside, where I could examine them better, and most of the scale is on the stems, which seemed strange. I got a terrible infestation of those another year - I'm sure that year with the "sticky stuff" all over them, and many of the leaves had them underneath, and curled up from them. I got rid of them using some pyrethrin spray, followed by orange oil. Now, when I take any plants indoors, I spray them several times with that orange oil, which seems to eleminate just about anything, though these things must have been brought in later on.
I have read somewhere that kaffir limes are resistant down to a brief frost, so I figure they're OK in the high 40s. I always put them out a little earlier than the curry tree, which I've heard is resistant down to 50Â°.