Gallen (shoulder) threw off a mound Tuesday, Steve Gilbert of MLB.com reports.
Gallen reported feeling fine following the session, which is an encouraging sign for the right-hander who started feeling stiffness when he ramped up throwing in December. He's expected to throw one or two more bullpens this week, which puts him slightly behind other starters. Gallen added it was too soon to tell if he'll be delayed at the start of the season, but he told Nick Piecoro of the Arizona Republic that if he is behind schedule, it would not be by much.