Maybe only slightly related, but where I grew up the age of consent was 16 but we there's a 'close in age' law of 3 years (so, 15 and 18, 11 and 14, potentially).
And I'm just realising how much this (apparently) influenced my perspective. Somebody above mentioned a 14 and a 16 yo and how this is 'a delicate issue' and I was just thinking... well, that's just normal, isn't it?
Weird, how stuff like that can influence us.
Anyhow, as mentioned above. I don't think there's enough here to be concerned about. That's behaviour classified as friendly, seriously. Teens seem to also write stuff like 'love you' 'will you be my girlfriend' 'you're so cute/hot' etc and they don't actually mean it sexually/romantically.
What else? He's 14. He is not a baby. Seriously, when I was 14, 14 yo boys (and girls) weren't babies. Sure, we were immature little shits. But not innocent babies.
If she does do something that's a reason for genuine concern you do have to contact the school.