Brisket injection help

Thirdeye, the site is terrifc and has been a fantastic resource for me. I have had my best brisket efforts as a direct result of your site. The last time, I tried the injection at the 180 mark as the brisket was coming out of the plateau. This seemed to drop the meat temp quite drastically and I assume added a lot of time to the cook. Is this normal or should the injection be heated prior? Any insights here would be much appreciate. To be clear, everyone raved about the end result.