Fitzgerald and five members of his coaching staff attended the Longhorns' bowl practice and watched film, but sources close to the situation said it was a typical visit for a coach whose team isn't preparing for a bowl game. Fitzgerald said in a text to ESPN.com that it was a "standard drop in."
A Texas spokesperson did not return a request for comment.
Fitzgerald is one of the more than a dozen names that have been mentioned for the Texas vacancy following Mack Brown's decision to resign Saturday after 16 seasons.
In eight seasons as the head coach at his alma mater, Fitzgerald is 55-46. Northwestern finished 5-7 and 1-7 in Big Ten play this season after going to five consecutive bowl games.
Texas athletic director Steve Patterson said Sunday he'll seek candidates with extensive college football coaching experience but that there is no timetable for making the hire.
ESPN.com's Adam Rittenberg contributed to this report.