What do u think, was that alright to say or...?

I had a job interview today and the person interviewing me, really nice lady, she said that I'll pass through to the next stage and that she'll send me an email soon to confirm the date and time.
So after I got the email and I confiremed it, I said "That's great, thank you and happy Valentine's day!".
Was that ok, or I shouldn't do that ever again?