Is the answer its happy or hears rustling bags
As you lifted her? Where do the rustling bags come into it? What kind of squeak?
If she randomly squeaked when you lifted her maybe she just didn't want to be picked up and she was stressed out.
If there was rustling bags somewhere (?) she might have been wheeking for food. My two both associate the sounds of bags with veggie time and get very vocal.
I still don't really understand your question. I hope this helps somewhat anyway.