Was this the proper thing to do?

We were all over my BF sisters house and I placed a napkin over my hand before I picked up some chips (since she didn't have any utensils to pick up stuff ) and they asked what I was doing and if I felt my hands weren't clean I should wash them! as if they were offended that I had done this....I felt like I was doing the proper thing. I just laughed it off but what was I supposed to do? I didn't want to put my hands on their stuff! LOL