Aye, redstone is becoming less reliable with each subsequent update. Since tu11, I've found track switches sometimes stay activated even after the minecart travels over them. Or sometimes buttons will act as switches, remaining on after the 10 ticks. These bugs happen almost always with redstone contraptions that span two separate 'chunks', so perhaps thats related to it. Smaller machines seem less apt to getting 'stuck' on or off.
Whatever is going on, the redstone mechanics could really use some attention & polish. Even if it at the cost of other aspects. Because lets face it. Redstone is integral to minecrafts success.