"It may be that some significant announcement is being clarified or is about to be made, that's an option, but I really don't know.
"It's not a private meeting - although obviously they can exclude people from meetings - but I would say that was a little unusual."
ASSPA secretary John Heyes said having the press at the meeting would have constrained the openness and frankness of the discussion.
The Minister said a great deal of the meeting had been about the rollout of ultra-fast broadband, which was taking longer than anticipated, which had frustrated some principals.
"There's a desire for all schools almost instantly to have access to that broadband. It hasn't happened as fast as they would like, but that's just a practicality.
"I understand that frustration, but there are budgetary constraints and we are reliant on our partners in rolling out that fibre," she said.
Ms Tolley said there had also been discussion about the Trade Academies initiative, the Youth Guarantee Scheme and newly introduced search and seizure guidelines for drugs and weapons in schools.