E.S.
I think babies are "programmed," like others said here, to recognize their mommy's scent, and yes, when hungry will latch onto anything/anyone. Funny story: One time, my daughter latched onto my MIL's arm, and went right for the breast of my very pregnant friend.
Take it in stride. The new mom will be glad to bond with you, and you with her and the baby!
And don't cry over spilled milk :-)