You may still get the notification even running Infamous. I was running the earlier builds before the official jelly bean update and I received it a few times myself. Even got bored one day and tried to let it update. It downloaded but won't apply since it wasn't the stock recovery. Just figured I would share that.
Sent from my dark hole called an office.
YUP Sammobile is holding a 732.8 MB 4.1.2 T999 update officially released, unless I'm having a hard time reading it on my 28" screen it's legit.
http://www.sammobile.com/firmware/ in the search type T999 and see if someone else can confirm the same info.
Downloading: T999UVDLJC_T999TMBDLJC_TMB.zip | 732.8 MB
http://www.hotfile.com/dl/191743281/1c0c7ef/T999UVDLJC_T999TMBDLJC_TMB.zip.html