There could be many reasons behind the disappearance of your comment. It could be because of a glitch and that it wasn't actually posted or your crush could have deleted it. Each of those possibilities have more reasons that goes behind.
Anyway, considering that you are asking this in the relationships category, I'm assuming you don't care as to the possible reasons as to why your comment is gone if it was due to a glitch problem. You're here because you are concerned that it was your crush's doing and you want to know the reason behind that. Well I'm here to tell you that if he deleted the comment, then no one will ever truly know except for him. So if you are suspecting that he deleted it, you can ask him.
But from personal experience, it's best to keep questionable activities on social media from leaking into a conversation in person. I personally don't find it a problem but more people seem to think of it as awkward if you talk about something that happened over Facebook, Twitter, Instagram, etc. With them in real life. And from what I know, this is especially true with guys. I don't see how it's a problem or how it's awkward but that's just how it is. Point is, you can ask him about it you really want to know but I think it's best that you don't and just let it slide for now. If this continues to happen, then it could be a sign that he doesn't want you looking all over his pictures or he doesn't want other people to know that you've been seeing his pictures for whatever reason. Either way, then he's just being immature and you are probably better off liking someone else.
