iTunes Reviews - Reviews are being written but only star ratings are showing up.

Here's my situation:

1. I ask users, openly on Twitter, to review my podcast and let me know what they think of it.
2. Users go and write a review
3. Users tell me, "Hey, just wrote you a review! Think the show is great!"
4. I thank them and scurry off to read what they wrote

Here's the problem: their textual review isn't showing up, only their star-rating. Let's take Saturday as an example:

I had a popular author on the show for an interview of his new book. Brilliant interview, smart guy. On Sunday I touched base with him, thanked him for coming on the show and giving us the opportunity to speak with him, and asked "would you mind writing a review of the show to let us know what you thought of the whole thing?" He obliged immediately, returning an hour later to let me know that he'd written a review.

I knew that his review wouldn't be present immediately, of course, so I waited until this morning to check in on it. When I did I found that his Star Rating was there, but not his written review.

This has happened on numerous ocassions. I'm sure of three incidents where a review was written but never show up - even though it's corresponding Star Rating did.

I'm aware of the different stores - all of these reviews exist in the US store, though I suspect there are a fair amount in the UK and AUS stores that aren't showing up either.

Note: this doesn't happen all the time, I do have a few written reviews that are showing up.

Can I get some help on this?