It's all about the way it's done isn't it?
For the people saying its a shame that gp can't love their gc... That's really not the point, of course they can and it's something to be treasured and encouraged.
But grand parents trying to take over and be more parent than grandparent is a problem! It's about not asking and collaborating with parents, and trying to compete and override parents. And also, a small thing becomes a big deal when it's in a context of many many small things adding up to feel unpleasant.
I too was going to write a stocking thread 
. So I'll write it here in solidarity with you! sorry here follows a rant...
My parents, especially my mother has massive overstepping boundaries history. Last year she had a hissy fit as 'shes jealous of me (her only living daughter), and why did I have to come up to theirs with my dc, aparently i 'push her out' as its much nicer when she's allowed to be Ds's mum!!!' she saw nothing wrong with this, totally blatant and expected immediate sympathy due to her being jealous'.
She even said 'it's ok for my dad (her husband and Ds grandpa) as Ds father is not around, so that gives him a role in Ds life, but because I'm around she doesn't have a 'role'" '... Err my h isn't around because he was horribly abusive to me and neglected his baby, and then left me when I became ill and couldn't pay for him anymore. But she'd rather Ds had no daddy and preferably no mummy either. Nice woman, always was a b*tch. I had to have strong words with her when she started to physically hold Ds back when he was crying 'mama mama' and trying to get to me. I can see my dad wince whenever Ds cries for me as he knows he ll get it in the neck later - she has to take it out on someone, of course.
I told her one more thing like that and she'd never see him again, be foul to me all you like, but do anything to harm my child and that's it. so she's backed off that at least.
She then gave me one cheap and rubbish present, and Ds a huge amount of presents, piles and piles... And refused to speak to me as i also gave him lots of pressies (like err, a parent does). Even at 2.8 yrs, Ds was upset and kept trying to give me his presents... He's an adorable little boy who always wants everyone to join in and share and be together.
She is soooooo disgustingly self centred, and no amount of including and kindness ever make up for the fact that I won't conveniently push off and let her play mummies with my child.
So this year, they came to mine, and I did stocking for everyone (to avoid last years unpleasantness), which is told them I was doing from about oct onwards.
My mother waited til I went to bed and then filled Ds stocking up completely with her presents! I tried not to fall for this ludicrous behaviour, but did end up taking some out and putting a few of mine in. Oooh the looks of thunder and death that were pointed in my direction in the morning. Ugh.
Now that is a woman who does indeed Is over stepping!