I find myself doing that a lot but I just do something else for awhile and just let it flow. I have in the past stopped being interested in certain things but It's not that I stopped being interested in everything and I also found new things to enjoy that replaced the old. I believe sometimes we grow out of things or grow bored of the same things all the time. I don't think it's always a bad thing.
If it does seem to be negative though or you really don't think it's just a funk you should share it with your t. Or just tell him anyway. I don't really want to tell you what to do lol.