When I was stroking Tuppence earlier I found a little almost pea-sized lump on her side, near her hip. I'm hoping it's just an insect bite. She's fine in herself and doesn't seem bothered by it but, needless to say, it's a bit of a challenge having a good look!
How old is she. Lady is coming up to 9 years old and is covered in those fatty lumps that Labs seem to be prone to getting. Could it be one of those. I think if it doesn't go down in a day or two I'd get her checked out at the vet.