Coincidences

What are the causes for such odd and fascinating things? Some people may say there is a cause for everything, which there certainly is for most things. (Example: My friend and I both have the same exact flowers by our mailboxes in our yard- reason: a group of girl scouts volunteered to plant flowers for one dollar by mailboxes in 2005) But I am talking about a small example of my professor and I running into each other at the grocery store. It definitely has not been at similar times. I do change up my grocery stores. And it has not been connected to -anything- I can think of. She also does not live close to the store, she does not go everyday (just on the days I do apparently) and we do not go on every tuesday or something. It has been random days of the week. Thus, I find no explanation. That I would call a coincidence.
Is there some higher power with a plan? Some people reason with this ideology.
However, I take the I Heart Huckabees approach that everything is connected. How? I use my own logic. Our existence is of molecules connecting everything in the world. Of course you know that atoms and molecules make every tangible material in the universe. They are what make matter possible. I use this in the way that when something becomes connected, it stimulates these atoms and molecules, creating a reaction within us. For example: have you ever "felt" someone looking at you? Or thought of someone and they called you? Or felt comforted just by someone "being around you". I feel like once the molecules and atoms recieve such stimulus they want it more and more and thus, it creates coincidences. Or what we think are coincidences.
That is one explaination. Then you get the unexplainable things such as a man who receives a heart transplant and dies the same way as his donor. How does that happen?
Everything is connected somehow, but this I would not know how to explain. It makes you wonder though, what is out there, why are we here, what are the chances, and if something higher exists.