I'd guess that something else happened on your EQ report, like an added account or increased utilization. SW will give score alerts from time to time and we all have the tendency to assume that the only account impacted (assuming this was the only account disputed) is the cause of the score change. Unfortunately, that's not always the case. For example, I once got a SW alert that my FICO score increased 20 points. Why it said? Because I added an inquiry. Now adding inquiries won't cause score increases. There was a collection that fell off, that SW won't pick up on, that caused my score to improve.
There are a couple of ways your score could have been impacted by this TL alone. One is if the status updated to a newer date and if Citifinancial added some lates. You'd have to pull your reports from somewhere to see how it now reports to EQ. Another way is if this Citifinancial TL reported as a revolving, though I don't think that's the case here.
Absent the two ideas above, you may want to pull EQ from somewhere just to see if anything was added or if anything is missing. Check utilization too which is the most common culprit for score changes.
