It seems Gronkowski had a good reason not to show up at the voluntary program, although it's one that probably will not fly too week with Patriots coach Bill Belichick.
"Training for this dirt-biking," Gronkowski told NBC Sports Boston while attending a Supercross event on Saturday at Gillette Stadium in Foxborough, Mass. "I've got dirt-biking skills to work on."
Gronkowski has not been committed to returning this season.
A five-time Pro Bowl selection, Gronkowski has two years remaining on a six-year extension he signed in 2012. He is owed $17 million in base salary over the next two years. He is due to make $8 million this year and has a $250,000 workout bonus.
Gronkowski, who wore full Supercross riding gear Saturday, was asked if he had any thoughts to share with New England's fans.
"They're going to see a freek-a-leek when I come back. That's what," said Gronkowski.
Quizzed on if that means he plants to return, Gronkowski replied: "Maybe!"