I installed the combo from DTD in December. Had the tires set at 28 psi and the TPMS sensors set at 24 psi. I did a chalk test and aired down my tires to 26 psi. On two occasions, once today, the TPMS dinged when starting with the indicator flashing to start and then staying on. Then, after a couple of minutes, it turned off (no more indicator light). The last time this happened was a few months ago. Any idea what's up?