Yes it's written all over the screen in LARGE letters when you go back to the start page. I also notice it quite often when I stay in hotels so I know most hotels use it.

It's still a bit strange they started upgrading you so quickly.
I mean sure they could see the potential of future business, but that could be said about lots of guests and upgrading everybody every time would simply not make sense, a hotel is still a profit-making company which has to sell some rooms as well, not upgrading everybody.
Did anything happen during the first stay (either very negative or positive) that may have influenced them to decide to pay extra attention to you if you would return (which you did)?
If they recognise you as a "frequent guest" the normal hotel practice is to write the surname in capital letters i.e. Mr SMITH instead of Mr Smith.
It is a simple, yet very efficient way to let all staff know it is a loyal and important customer who deserves a bit of extra attention.
If it's written in capital letters in the system it will be written in capital letters everywhere, on all lists, telephone screens, and on the bill and room service slips where you could notice it.