This was posted on another message board:
Per Matt Reynoldson of Husker Online:
Here's what I know:
Senior football players (the only sample size, may have been more) received a notification on their phones to attend a meeting. It's not confirmed that it was a team meeting.
This happened around 1:30 p.m., two hours before the "scheduled" start of Tuesday practice (for those of you that played high school/college sports, you know that if you're not a half hour early, you're late).
There is no confirmation that it was an "emergency" meeting either, so it very well could have been a direction to just show up early to the facility for a pre-practice meeting.
Since the players who received the notification were seniors, keep in mind that Friday is their last game. From how I've understood it in the past - could be wrong - they plan out the Senior Day festivities early in the week and typically don't take time out of the day-before-game walkthrough.