A Milkshake and a Wink?

I treated the kids to a milkshake at Sonic this afternoon. When I arrive at the pick-up window an attractive, yet mildly masculine (I know, a strange combo) says, "That's $4.01, Babe." It caught me a bit off guard that a woman would use the word babe when speaking to another woman. She takes my money and says, "Thanks sweetie." Humm? Then a moment later I look up and she's looking at me, smiles and I swear I think she winked. Was she busting a move, being friendly, did she think I was a guy? Very strange.