They issued that bulletin a while back. Ruger says some guns do not have the two halves of the internal chassis fastened together correctly, and "only a very small number of pistols appear to be affected".
This is an update, changed to a higher serial than before, 369-89043. It must cover nearly every SR ever made. I just bought my two a month ago, and their serials are lower than the one given now. My serials are 369-82*** and 369-84***, 5-7 thousand higher than specified in the first bulletin.
It basically says if your SR is below 369-89043, and has experienced a slack trigger in SA shooting , you may have the problem. That's magazine in, slide forward, hammer cocked, safety off and you have a dead trigger instead of SA trigger. Also, if you have the problem do not trust the decocker.
They say if you haven't had the problem you gun is not affected by the bulletin. So I'm cool. Mine operate fine with 50 rounds apiece so far and additional cycling in my den.