I went through the stages of gurning/ jaw clamping with elvanse and its died down but does come back every so often as I've got to higher doses.
What I have only just noticed though is that I grunt. It's weird, sat in the office and heard mself every so often just a gentle "gnuugg"! I _think_ it's because I'm subconsciously holding my breath occasionally and its more of a exhale through closed mouth, but I'm really not sure.
I have met people in the past who I've noticed done similar, and just getting a bit aware of it. It's not a problem (I don't think) just unusual and I'd be interested if anyone else has experienced this and is it transient or just a thing I do now!
Looking though the sub, I only found one post from a lady who said she'd found herself gently "hmm, hmm, hmmm' ing every so often so similar but not quite so.