Minecraft glitch - sheep walking through fences?

Okay my sheep are literally just walking through the fences now, they aren't even being pushed into it.
I'm playing Minecraft 1.7.4. Wasn't this fixed in 1.6.2?
I literally just went to my sheep barn and the red sheep walked over and went through the gate.
Please help.

This is my barn:
image

Added (1). @Coraline,
I play on my laptop. It's been happening a lot and I shut down my laptop when I go to bed.

Violet

I've never posted mnecraft… But I get A LOT of glitches in my games. You should try restarting the device you are playing on. The glitch will probably go away. Hope I helped!

Coraline