My professor wants to know if his recommendation is helpful

Several weeks after I received the recommendation from Professor M, he sent an email to me and asked me about the result of my application to a graduate school. He wants to know whether his recommendation is helpful and my application is accepted or not.

Although I have submitted my application and supporting documents to the graduate admissions, the deadline for the program I have applied for is on the 18th April.

The only message I received from the graduate school was that they had received my application.

I have no idea whether my application is successful or not, but the email from professor M made me nervous.

I can see that there are a lot of professors here. I guessed that some of you had written recommendation letters for your students. I would love to know this:

what were your reactions when you heard of your students telling you that their applications failed or your recommendation letters useless?

I feel scared when thinking of this situation.