Gab used to love doing this too. She thought she was so clever. People used to comment on how strong she was with standing and with holding her head up during tummy time.
She still went through the crawling stage then was walking confidently by 14 months. I wouldn't worry about it. I think it's only an issue if bubs is constantly put in a walker or in a jolly jumper for hours on end, iykwim?