My dog pushed herself with two back legs?

She just came back from playing around in the backyard, tehn my dog sat down and pushed herself/moved herself with her two front legs while her two back legs just sat there. I then called out her name and she walked up to me normally, but this is the second time it's happened. Should I be worried? My friend says it's just itchy, but.. need to be sure

Do you express her anal sacs frequently? When she does this, you should express them. If anal sacs are left full for too long, they can rupture. A lot of dogs try to express their own anal glands by scooting on the floor. Most people can learn to express anal glands by themselves. But, there may be several other reasons your dog is doing this. Sometimes dogs may scoot when they have rectal polyps. Matted hair around the anus can cause the same thing. Her anal sacs may be inflammed. Or, she could have a perianal hernia. Another possibility is a colon tumor. Perianal adenomas can also cause a dog to scoot. You will need to take her to the vet. Sometimes constipation can cause a dog to scoot. The same goes for colitis. Colon cancer can also cause a dog to scoot. So can bladder infections. And perianal fistulas. And lax rectal muscles.