You should be fine, I forgot to plug my water pump back in once and didn't realize until I was sitting first in line in the left hand turn lane at the busiest intersection in town. It was off the temp gauge by the time my light turned green and I was able to pull over and plug it in. I was more worried about cooling it down to fast than I was the actual temp. No issues and it lived on for several more years before I pulled it for another engine.