Some are very sensitive to sulfite, so it is possible to get that much,
but it's an individual thing. Also, if you put in sulfite in the form
of Campden tablets and didn't get them completely dissolved, you can
get a white residue on the top of the liquid in the carboy, and your
headspace will have more of a sulfite smell than the wine.

I'd try the titrets (I've had good luck), but take a sample from down
within the carboy, if you understand what I mean. Also, smell the
sample, and see if it's as strong as the sniff you've already taken.

Rob