The temperature probably wasn't significant, unless 40 degrees was the high.
My personal rule of thumb is: If storing batteries outside in free air (not in a compartment, but also not on cold concrete), heat them when nighttime temps are below 40, and especially below 30.
But yours are probably in a compartment, and big batteries take a long time to get cold. They are very dense. I don't think one night with a low of 40 would get you unless you were very close to the line already. You probably took a SMALL hit from temperature, but not a big one.
