We LOVE this about our dog. I don't know if it's a saluki (mix) thing, but she is a right old grumbler, you wouldn't know she's an 11-month old female as she sounds like a 90 year old man sometimes.
Every time she settles down somewhere, she does this old man grumble and groan.
And then when she yawns, she makes a really protracted squeaky noise, almost singing. It makes me laugh every time, she's such a character.
She's quite vocal generally - when she's frustrated, excited or curious about something, she makes these noises which sound exactly like Scrappy's "Uncle Scoo-ooooby" and she's a right old whiner as well. I used to get really paranoid about her being upset about things when she was a puppy, but now I realise it's just part of her character and she is a massive drama queen