New irons- Wrong flex?

I am re posting this question here on the advice of another forum member.

To set the stage, I am very much a beginner at the game. I average in the 100-110's for 18 holes. I am just know starting to shop for new equipment to replace an ancient starter set I have been playing. My driver swing speed is about 90mph on the simulator at the store. I am 36.

I recently picked up a used set of Callaway Diablo Edge irons. They have graphite shafts with an "A" flex. I purchased them with complete ignorance of what the shaft flex meant, I only know that I hit them the straightest and farthest on the simulator in the store. On the course, they have improved my game considerable in that I have more loft and accuracy than my old set. However, after purchasing them I took my first lesson. The instructor says that the "A" flex is too light for me and I should consider exchanging them for a "R" flex. Is this really a problem? Or will it become one as my game improves?

Thanks

It may not be a problem now but it will become one. If your driver club head speed is at 90 the average players 6 iron swing speed is 15-20 mph slower with the 6 iron. That would put your club head speed in the 70-75 mph range. Just with that info alone I would have put you in a regular flex. As your game improves that club head speed will go up. If you get to 80+ we need to start looking at a stiff. To play an "A" flex I want the club head speed in the 60's tops.

What will happen and what to look for. If you start to hit solid shots that go high and stay out to the right or drift right this is a good indicator that the shaft is too weak. Keep working with your coach and when you start to make good swings and the ball stops going where you want it to then we need to start looking into shafts.

Thanks for the response. That answer seems to be the general consensus I am getting. I guess I need to look into a different shafted club.