Redstone torches re-lighting without updates

Was designing a farm and caught my redstone torches and system doing weird stuff when accidentally misplacing a bit of redstone dust. They seem to be self-updating and re-lighting themselves. I've been doing redstone for a minute now and I've never seen this happen before. Is this a bug or an intended feature due to parity and updates? I may just be a moron but I'm almost certain a torch needs an update to re-light and I dont see anywhere that would receive an update.