Yeah, if the temp is that cool outside, and You haven't changed anything else it wouldn't follow to be only heat related............ was the garage warmer than outdoors
by any real amount? If the tank were mostly vapor and you pulled it in to a warmer location, a lot might get pushed out the vent line from the tank. you wouldn't be
able to see that, but the odor would be by the rear wheel more so than the engine.