You probally went thru or passed a vein coming up or a blood vessel even. That is a common accorance. don't let it bother you. Your gear probally did not come out, if it was injected into the muscle.
Billy made a comment that he does that I also do, right after I take the pin out, I immediately place a cotton ball over the site to prevent blood from squirting out. (no pun intended). I hope you asperated before you pushed your gear in? If not then you may have hit a BV. If you did, then you might have went directly thru a vein. Don't worry. It happens.