It's been a couple years since I lived alone, but I remember it well. I'm not sure if my behavior was actually weird. I mean, why would I close the door to the bathroom...it's not like anyone is there, did I really require additional privacy from my walls or dogs? The same goes with walking around naked (Although, I didn't do that much...I was more of a A Shirt and boxers kind of guy).
I think living alone allows people to fully be who they are without concern of judgment and social politeness (meaning: clothes are required when certain folks are around and germs are not cool to share unless engaging in certain activities)
By the looks of this thread it seems certain behavior is shared by many...so, to me that would be common behavior not weird.
Now, that being said...I have been told for many years that I am eccentric (the polite term for weird). I have habits...I lived with a very strict schedule and in many ways it was ritualistic...this created a calm for my brain and soul. I am still that way on many levels...in my brain I create a schedule for the day and I stick to it unless I absolutely have to veer from it. I have a lot of "quirky" behavior that when others view them raise an eyebrow or make comments. I personally don't find them quirky...but it seems others do because they don't understand the reason behind it.
It's all perspective really...I have lived a different life, with different cultures etc. I meditate, I work out, I pray, I eat certain foods and food combinations because my life experiences. Those things alone could cause someone from a different back ground to view me as weird.
So, am I really weird? and if so was it truly created by my living alone? Maybe, living alone just gave me the room to develop the true me?
Hmmm it's much like the old question: which came first the chicken or the egg?
I may never know...