When placing a redstone torch on a block of redstone it lights up for a split second when it shouldn't. That's because a block of redstone prevents the redstone torch from lighting up as we all know.

How to reproduce

Craft a block of redstone and a redstone torch,

then place the redstone torch on top of the block of redstone, it's gonna light up for a split second when it shouldn't.

Observation: Redstone torch lights up for a second when placed on a block of redstone.
Expectations: It shouldn't light up since a block of redstone prevents it from lighting up.

Note: The torch also activates any redstone nearby and then deactivates the redstone as shown in the video.