What is this firefox dnf update line about?

[Tom Horsley]

Just curious. Every time I run dnf update, I see this at the
beginning:

Running transaction
  Running scriptlet: firefox-60.0.1-3.fc28.x86_64                           1/1 
  Preparing        :                                                        1/1

Then it starts the "real" update:

Upgrading        : glib2-2.56.1-3.fc28.x86_64                            1/31 
  ...

Why 1 of 1 to start with (and always firefox) then switching to 1 of N
for the rest of the update? What special magic does firefox have?