In a normal sentence, you don't include "did" before the verb, like this:

I got some promising leads.

But you put "did" in there when your sentence contrasts with what someone said:

A: Did you make any sales?

B: No, but I did get some promising leads.

Of course, you can see the same pattern with other helping verbs:

I'm not afraid of the dark. I am afraid of wild animals, though.