(someone) did (do something)
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.