One of my sensors went off last week. Took it to a tire shop and found my LF was down to 18 pounds. (Was 32 2 weeks prior). Tire guy put 4 seconds of air into the tire and told me I was good to go! I went, alright... Went to tire shop 2.
They pulled my tire off the truck, then off the rim, and found that the inside casing was seperating. Tire shop 2 sold me 4 brand new tires.
Just be sure the sensor isn't really trying to tell you something important...