This is not necessarily shown as an Item in your inventory. I started receiving this error when I was simply given a purchase at a store [MODA]. I never opened it, never put it on, and there wasn't anything worn in my inventory other than what I expected, and it would come up every time I teleported to another sim.
It did show a bridge script under World > Parcel Details > Script Info, it shows up as Firestorm LSL bridge, HUD Center 2. Unless that is the original Firestorm Bridge, I'm guessing it's something the give script did from [MODA].
Restarted Firestorm, and haven't received the error. Will update if it's still there.