Rooster making odd noise when crowing

I don't know whether this belongs in this section or not. I don't even know whether it's a health thing or a behavioral thing.

The rooster in question is an EE, almost a year old now. Occasionally, after he crows, he makes this high pitched squeaking sound and shakes his head. It almost sounds like hiccuping or something. He's been doing this since he learned to crow, and it's only him... not any of the other roos. Well, this afternoon I was passing by and he started to crow, but before he could finish the note, he lowered his head and made the high pitched 'hiccuping' sound. Then he just stood there, hunched over, and repeatedly making the sound. After a few seconds, he seemed to return to normal. My first thought was that he'd thrown out his vocal cords or something, but he's crowed since then.

What would cause this weird noise?

Aside from this, he seems very healthy and active.