IM injections

Gosh! I'm trying to help out at a clinic and for the first time, am having to deal with pedi patients. It isn't easy! I've given many injections, but today, I gave one on a pediatric patient and some of it leaked out! I've never had this happen to adult patients. I've heard of this with the new NOvolog pens our hospital is using. A few nurses give the injection and don't wait long enough and it leaks out when the needle is pulled out, but the needles are tiny. I've never had that problem. But with the child today, I had the needle in far enough and as I injected it just seemed to come out. Again the needle was in pretty far. Why on earth did this happen? Do injections need to be done differently on kids? This patient was about 10 years old. I feel really stupid! Thanks!