MEGA Emma Stone is worrying fans as photos of her in a glamorous evening dress spark weight worries. The Mean Girls star, 37, was featured in a February repost on X, with the photos showing her in a stunning black gown as she promoted designer Louis Vuitton. Honoring her partnership with the luxury designer, Emma looked classy as ever in a cut-out dress with a backless design, flaunting the figure that some fans thought was just too slender. Emm…