Dick,
I posted a reply on your original post regarding having your 624 checked. Oddly enough, my serial number is also in the AHT27XX range and Mark Rossini at S&W checked mine and said it was not in the recall range.

I'm not sure how many of these 624's they make per hour, but we're within 50 guns or so of each other (my actual number is midrange AHT2700's). I also asked if they were making their determination by serial number or the date in the grip panel. He said it was based on the serial number as grips could feasibly be exchanged.

I saved the e-mail response from S&W and placed it in my box as it does not have a red circle "C" on it either.

In any event, I would ask for a high end replacement if they keep the 624. Although it was ONLY a 3 inch 624 when made, it has certainly appreciated greatly. The grips are a good indication. They were probably $35 or so new and now easily bring $250.