To do or not to do?

[Siôn]

I love English. I'm doing it for my degree and I could not be happier with it, however, I recently discovered that my teacher lives in the same apartment complex as me... Not that bad, I can live with that, the problem comes when I'm day dreaming and he sees me murmuring to myself and writhing my fingers. 

A bit of background, my teacher and I have gotten along amazingly, we've really hit it off and he's one of the best teachers I've ever had. After he saw me murmuring and writhing my fingers in a similar fashion to Mr Burns, he then asked if I was okay. My answer was yes, of course. How could I not be okay, I'm just chilling in my world, talking to fictional characters bu NO. H has been asking whether I'm okay for a fortnight now. I appreciate the concern, but it's tiring now, so I have a query:

             Should I explain MD to him and ease his bombardment of questions OR, do I just keep on answering 'yes'??

[Siôn]

Meghan, he lives in the same apartment complex as me. I was walking up the stairs murmuring to myself and he was just leaving his apartment. We created each other painfully and walked briskly away from the scene.

[debbie downer]

just keep on answering yes, i know he's a nice guy it's none of his business what you do. how did he see you daydreaming in the first place?

[Source]

Maybe "yes" isn't good enough. Try telling him that there's really nothing to worry about. Do it politely, but firmly.