my border collie x snapped at my little four year old sister yesterday, should I be worried? His never done it before.. she cuddles him all the time & kisses him on the head sometimes and I think that's what she was doing at the time.. I try to make sure she doesn't hassle him too much. I'm not sure whether he snapped as a warning or? he appears to like her cuddles & tries to kiss her back when she kisses him.

How old is your Collie?

I would be very careful. While it may have just been a warning snap with no actual ill intention behind it you never know if they will just 'snap' one day and have had enough.

I know this sounds obvious but never leave a child unattended with a dog, even the sweetest dogs can get a bit upset with a pushy child.

Does your sister live with the dog or was she just visiting?

At 4 she is quite capable of learning how to behave properly around dogs so it might be time to give your sister a few little lessons.
Just teach her that dogs do not like the be crowded or cornered and that petting him is OK but cuddles and kisses are not.
Teach her that she should only touch the dog if he knows she is there so she doesn't surprise him as well.
And you can also start to teach her the warning signs of when a dog is upset or does not like what is happening. (ears back, growling, baring teeth, pulling way etc. )

Thank you, I've been trying to, she knows not to hurt him and to be gentle its just the cuddling thing. Thank you :)

Yeah, they mean well wanting to give the dog cuddles but some dogs just don't like it, especially with little ones.

One idea I like is making up a chart with her name on it and days of the week... when she does something good with the dog, for example just sits next to him and pets him then she gets a gold star on her chart.
If she gets gold stars all week then she gets a special gift at the end.
If she misses a day and does something that she has been told not to then she starts over again the next week.

As always shazamataz's advice is always good.

What could have EASILY happened is that the daughter stepped the dogs toes by getting too close. She may not be aware that she needs to watch her feet when close to the dog.

Thank you both of you (: yeahh she has just got a chart with stickers so ill see about adding that to it good idea :) I'm forever reminding her about where she steps around him.