Upon rereading that passage in Matthew 18 I can see how you can make that argument.
Mt 18:3 And said, Verily I say unto you, Except ye be converted, and become as little children, ye shall not enter into the kingdom of heaven.
Joh 13:33 Little children, yet a little while I am with you. Ye shall seek me: and as I said unto the Jews , Whither I go, ye cannot come; so now I say to you.
1Jo 2:18 Little children, it is the last time: and as ye have heard that antichrist shall come, even now are there many antichrists; whereby we know that it is the last time.
1Jo 3:7 Little children, let no man deceive you: he that doeth righteousness is righteous, even as he is righteous.