It certainly isn't a bad thing you are getting a letter. At least they don't think you are a total tool.
Let's face it, even though you think that the competition is totally one sided, with the program being the windshield and you being the fly, it's not.
The programs are competing with each other. There are a limited number of competitive applicants, and we as programs are competing for them. They certainly must like you to some degree, but can't say how much. Besides, it's early in the season, they may not have even created a rank list yet, and if it is made, it certainly is not what they are handing in in late February. A letter now is like your thank you note. It's designed to make you feel good about the other party, that's all. They want their name across your desk one more time. So feel happy, but don't pound your chest just yet. Keep interviewing.
When I was a student I got a few of these letters, and thought I was made in the shade..... until I had to scramble in March. I don't mean to scare you, I decreased my rank list to an unacceptably low amount at rank time. Don't do that!
You may get additional letters late in the game, after rank lists are made. These are more important, if the programs are ethical it means you are ranked, and hopefully higher on the list.