Missing pram part at nursery

This is such a weird post but when I picked my daughter up yesterday from nursery my pram was not where I left it and when I unfolded it the belly bar was missing. The staff were as confused as I was and I know for sure that it was on the pram because I can remember not strapping her in as it's only a short walk from the car to the nursery. As I'm sure you all know, it isn't a part of the pram that just "falls off" and it has to be deliberately unclipped on both sides - it was also folded so it would have needed to be unfolded and the belly bar removed and then refolded. I don't want to make random accusations but I can only assume that someone (another parent?!) has deliberately taken the belly bar off my pram. It was definitely my pram as it had a hairband and some receipts in the basket. I'm really annoyed because we've only just bought this pram. The belly bar is only £17.50 to replace but I just feel weird about the fact that someone has potentially deliberately removed it. I know the pram is left at nursery at my own discretion but I have to leave it as my husband usually picks up and the walk home is too far for him to do it without a pram. I don't know whether to raise it with nursery as it's a bit odd that someone would be interfering with the prams like this while waiting for their child to be brought out. Does it all sound a bit mad and should I just drop it? I just feel really annoyed by it.