Worried by mistake at restaurant

This morning at brunch I ordered a grapefruit juice. The waiter brought it out and after sipping about a fourth of the glass I gave it to my sister to try because it tasted strange. She said it tasted like it had champagne in it, which completely freaked me out. I don't drink alcohol at all and especially not at 9w3d. The waiter swore it wasn't, even though it was fizzy and not at all like any grapefruit juice I have ever had before. My question is this - if it happened to be champagne and I drank a fourth of a small juice glass, have I put my baby in serious danger? Trying not to freak out over something that's already done but hard not to with my first baby.