Hmmm..how can I ask what he mentioned in the rec letter? Is it proper to do so?
What does it matter now? If he is going to write more letters for you, it might be worth while asking, but I think your impact will be minimal. He isn't going to suddenly start writing really good letters if they sucked before.
One of my recommenders submitted the morning he got the emails. I'm pretty sure he did a good job (he said it took him 2-3 hours each), he's a smart guy and I provide a number of "cheat sheets" on what to include and what to avoid.
Either way, it's too late now, so....
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