My 45mm blade is the kind that auto-retracts when you let go, and ironically that's the only rotary I've cut myself on. Exactly the way maviskw described...something else in the bag pushed the handle in and I ran my finger right along the blade! Fortunately it was a shallow, glancing cut that barely even bled. More of a warning than anything else!! My 60mm is the quick-change kind that I have to remember to close but fortunately I'm very much in the habit of closing that blade after every single cut. So far....so good! (knock on wood)
Now when I bring my 45mm anywhere, I put it in a tupperware all by itself, so no more skin shaving for me!