Had a flat on the bike rack before going home last night. Changed tube, and about 3/4 of the way home started going flat again. was able to pump it up enough times to get me home. Decided to switchover to some Marathon Plus tires, patched the tube, and no problems on the way in today. I think I can feel the heavier tires (not sure what my stock ones were, but they were lighter), it was either that or the headwind, or maybe both.