It can happen any time!
I discovered my security light lens was installed upside down (it has weep holes in the bottom) when it fills with water to the wiring hole it runs into the wall system. Luckily it is a 2010 2900MK Sundance and only sat on the lot a few days. It was full to the wiring hole though.
I read this thread a couple days ago and then went on my way reading other stuff. This morning as I prepared to take my first cup of coffee, I looked out at our rig parked in the back yard (yes it is allowed here) and I saw that my doorside security light was one-third full of water. I knew immediately what was wrong after having read this post and went out to the rig and found the light was a quarter-turn off, the "TOP" inscription was at the 9 o'clock position so no water could run out the weep holes.
Our rig is a 2008 and I had just taken it into a local RV Dealer's shop about a month ago and had some work done, including checking the door-side security light. Well, guess that the mechanic didn't know how to put it back in place correctly. I got it drained and put back correctly, but now I'll have to watch for any possible water damage elsewhere in the coach.
Just thought I would share this because it can happen any time someone messes with the lenses and doesn't know how they are designed to work. Hopefully, mine didn't do any serious damage.
Victor