At 7 months, I'd say it's just a phase where he's experimenting with a new trick he's discovered. DD went through a couple of weeks after she discovered she could click her tongue that all she did was 'click click click' after months of babble. We've also had phases of teeth grinding and spit-bubble blowing (yes, charming!). At 23 months she now has a massive vocab and speaks in sentences, asks questions and uses pronouns, plurals and past-tense correctly... so no issue with language development.

I thing it's just a healthy and normal part of them practicing oral-motor skills. And, as others said, sometimes focus shifts onto developing, say, motor skills and language development stalls for a while. I would only see cause to worry if you've noticed regression in other areas such as motor skills or social engagement.

Hope that helps. oxo

PS. I know how easy it is to get yourself into a tizz about this stuff. I work in early childhood development and have practically turned myself inside out a few times scrutinizing behaviour and development! Try and relax and enjoy your little hummer... he'll be talking your ear off before you know it!!