I would keep answering his questions about what the words are, and throw in some alphabet books occasionally. I think there's a group of GT kids start out as whole word readers (not sounding them out). And then they somehow know how to read, without any real instruction except you reading to them. It's like they figure out the reading code without going through all the steps. (This was our experience with our son.) Our son did know his letters early on, though. We did have alphabet books around, and I'm sure we had to read Dr. Seuss's A to Z many hunreds of times.
DS also had some LeapFrog magnetic letter thing on the fridge, where you'd pop in the letter and it would have some annoying little song about the sound the letter made. He seemed to like that.
