one of my family friend asked me to deliver a package . am I over thinking this?

I'm going to asia this weekend and one of my family friend asked my to give a package to her friend since delivering packages are so expensive.

she said "its just some stuff you gotta give dont worry about it". but something about carrying a package that I dont know whats inside and the way she said it feels wrong. At the same time, I also don't want to offend them if this actually is a common thing people do.

should i agree to this or politely say no?