TST TPMS 507 System and valve stem Question

I recently installed my TST507 system right before we left for a 1,500 mile round trip excursion. It did a fine job, even warned me of one tire's excessive pressure due to the significant increase in ambient temps from when I first aired-up. I debated, but didn't have time to get metal valve stems installed as I'd seen suggested on some other sites. Well, I'd DEFINITELY recommend it...see attached pix.









My typical speed range was 57 to 61 MPH with a few incidents of 68-70 MPH for short (<30 seconds each time) due to steep descents.