i'd appreciate it for sure. it's a nice gesture and i think it's just common courtesy. i think it applies to all languages.
i have a hearing friend who is fluent in ASL and worked at an exhibition last summer serving root beer floats. a deaf customer came and ordered a drink in English and she took the order and spoke orally. but then before she gave them the drink, the man started signing with the other person with him. so when my friend noticed this, she switched to total communication (since she can only assume that one of them is deaf), and they seemed to very much appreciate it. of course that's different than signing just one word, but it's always nice when someone knows a few key signs. if you travelled to a different country, you'd learn how to order food, ask where the bathroom is, and say things like excuse me, and thank you, and "no tequila in my drink, please". (i learned that the hard way.)
