Getting/giving head

So I recently received oral for the first time and it was awesome! My boyfriend made sure I was comfortable and didn’t expect anything in return. The next day he went down on me again, this time I wanted to return the favor and give him a blowjob. When I reached for his junk he kind of turned away like he didn’t want me to touch it. I don’t know if it is an insecurity thing, a respect thing, or if he just ain’t into getting head. Has this or something similar ever happened to anyone else? I would love to hear and similar stories or advice!