Pat Flannery wrote:

I wonder if some of that was the after-effects of the CO2 scrubber
problem that occurred just before she got there.

No, the smell reported was in the vestibule between the Soyuz and
station, which is exposed to space before docking. The "burnt" smell
that areas exposed to vacuum acquire has been noted by many space
fliers
(and was pointed out to Ansari as "the smell of space" by the more
experienced crew)

quoting from http://spaceblog.xprize.org/2006/09/22/

The time went by really slowly, but finally the moment arrived and they
were ready to open the hatch. Mike and Misha called me closer and told
me to take a good whiff because this would be the first time I would
smell "SPACE."

They said it is a very unique smell. As they pulled the hatch open on
the Soyuz side, I smelled "SPACE." It was strange... kind of like
burned almond cookie. I said to them, "It smells like cooking" and
they both looked at me like I was crazy and exclaimed:"Cooking!"

I said, "Yes... sort of like something is burning... I don't know
it is hard to explain..."