I just changed tires on 2007 Quest with TPMS. One valve was leaking and technician "fixed" the gasket in the valve. All are holding air and tires are inflated properly. My wife is on a road trip and after 400 miles of steady driving the "low pressure" indicator (in dash) went on and the TPMS wasn't registering one tire (presumably the fixed valve). Tires still holding air and are handling well. Anything I should look for or check? Should I plan to change the complete valve stem?