What is the meaning of this?

Once they all went to sleep, I sent a report to the Watchers.

In the end, it was my grandfather who suddenly called me after the report was sent.

I was surprised to see him calling me, but I still picked up.

"It seems like you have a habit for picking up girls."

The moment that I heard this, there was a bitter smile that appeared on my face.

I never thought that the first thing that he would say after I picked up would be to tease me like this…

There was a strong urge to hang up on him right away, but I knew that he wouldn't call me for no reason. So I didn't hang up in the end and waited to see what my grandfather had to say to me.

"Are you sure that you'll be able to handle them?"

This was the real reason he had called me.

The first part seemed to be a way for him to lighten the mood, but the second part was the real meat of the issue.