Make sure the sensor extends all the way into the
oil and isn't touching the metal pan, thus measuring the temp of the
oil pan instead of the
oil. And yes, this has happened before. The bung in the oil pan may not be letting the sensor extend fully into the oil to get an accurate read. When you remove the sensor again, stick a bent paper clip into the hole and hook it on the inner lip of the bung. Then measure the length of the bung and compare it to the length of the sensor. The sensor must extend beyond the bung in order to accurately measure the oil temp.
Don't worry. Your engine is running warmer than 140. It's either a faulty sensor or faulty placement. If you have a remote oil filter, you can try mounting the sensor there temporarily for a comparison.