EZ IO's...problems with leaking?

My EMS agency recently started using the EZ IO drill, and not too long ago we got to use it for the first time on a real adult patient (Code 99). It was very easy to use and we had definite bone marrow return, but as we tried to get fluids through it it appeared to be leaking which then made us question it's patency. It was also very difficult to give fluid boluses.

Has anyone had much experience with the EZ IO yet? We're wondering if it's common to have fluid leak from the site...the IO itself seemed very secure and when the hospital later started dopamine through it the patient responded well.

Thanks