Leaving aside the less-than-helpful responses, I have had crushes on people for as long as I have known what a crush was, and still do!
I just don't tell my wife about them!
Why would I? They are harmless, the mean nothing, they are an ingrained part of my psyche, and I enjoy them. To tell her would provide nothing in our relationship except the utterly unfounded sense of unease and mistrust which you are now feeling.
I think your boyfriend should not be quite so keen to share his every thought and feeling - especially if the result is of no positive value to you, or your relationship -in fact quite the opposite.
Don't worry about it, but encourage him to keep his crushes away from you - it is disrespectful.