Yes. As many have pointed out, 'crush' is inappropriate here. It actually means 'infatuation', according to the standard dictionary of English (OED).
One connotation of a crush in this (English-English) sense is that it's mostly applicable to adolescents: it's a kind of immature, often (though not always) unreciprocated infatuation, generally (though again not always) unrequited. None of that makes sense of a pre-school child. Although you might make sense of extending the idea of a crush to adults, it still would carry with it a connotation of immaturity ... but to speak of a pre-school child having a crush is, indeed, creepy.
Why so? - Because of the particular sexual connotation the word has, no matter how unrequited the crush be. And sexual connotations regarding children are definitely to be avoided in contemporary English society. Slavic custom might allow such connotation (albeit largely jokingly in specific intent): @Okeydokedeva's response earlier about 'gay friendly' gives that game away. But in English, definitely a no-no.
That's about language intersections. But, of course, such intersections are indicative as well as definitive. Slavic culture is different in lots of ways from British. (One of my children married a half-Slav; I've seen a lot of this at first hand.)
@Okeydokedeva you just have to grit your teeth and try to learn: we're all different, and added to differences of personality are cultural differences. And, well, 'When in Rome, do as the Romans do'.
In this particular case, @Okeydokedeva, it's probably too late. You just came across as too pushy. You were too pushy, in fact; we English - most of us - see that from what you wrote. But you can learn, for your own sake as well as that of your children. Don't assume everyone is like you; don't assume your own built-in cultural norms are universal or necessarily best; look around and try to learn (yes, about use of language, too); try to adopt some of the cultural habits of those you live amongst (even if you see them as worse than your own). (Tricky!) Live a happy life.
Good luck.