S-fronting in English?

[Jonlang]

Like the th-fronting (realising /θ/ as [f]) in some speakers of British English, I've noticed a kind of s-fronting in some American English speakers where /s/ seems to almost become [θ] but it sounds as though the tongue just touches the back of the upper teeth. I've noticed this a lot, but it only struck me to look into it recently when watching an interview with Jon Favreau who does it almost exclusively with his pronunciation of /s/. I can't say I've noticed this in Brits.

Is this a real shift in articulation or am I noticing something else?

Hers's a Jon Favreau interview if you want to see what I mean.

[Travis B.]

What I have noticed here in southeastern Wisconsin is the opposite of that - where a plain sibilant becomes palatalized in a variety of environments, including not just environments that would palatalize any alveolar or postalveolar consonant (i.e. before /w u ʊ ər/), but also before /p/, /b/, /t/, /d/, /tʃ/, /dʒ/, /m/, /n/, /r/, /l/, or /w/ (but not /k/ or /g/) and after /k/, /g/, /r/, or /l/. (Note that final /st/ generally does not undergo this if the /t/ is elided.)

[axolotl]

Hers's a Jon Favreau interview if you want to see what I mean.

I think he may just have an unusually dental idiolect. His /t/ and /d/ sound dental to me, unusual for most English.