I think all of us have done that at one time or another. I was private messaged by a new girl on another site who had read my story about it. Her PM took a scary tack because it happened when she had an actual mirror near the dilator when it ejected, and it cracked the mirror in her hand. Good thing it did not actually break it into slivers.
On my first experience, I did have a small muscle strain that ouched for about a day. Those dilators are made from HARD plastic, and those muscles do have heavy contraction. You should be fine, but ask the doctor if it is really bothering you.