I've never seen it before but my little barred rock, almost 3 months old, looks like it's trying to crow but nothing sound wise comes out. I can't post the video but this is the little one making funny chicken faces if it helps.
I love watching a young cockerel learn to use his voice.
Sometimes it can appear they are trying to clear their throat.
They do it in different ways and usually when it finally comes out the first few (sometimes longer) kind of sound like a toy with low batteries.
Enjoy your little man I hope you will find his voice as entertaining as I usually do.
I also love when they learn to call the Ladies, I have one that will almost purr to his Ladies. He is my little Romeo.
Scared me to death when I first saw it. I thought it was choking for some reason. With its white feet and little tiny comb I was double checking myself on its gender but abviously it's a rooster now. Wish the video was compatible I'd post it it's cute