I was just wondering if any of you guys have had your puppy ever eat sand?

I take my 4 and a half month old black lab, along with our 7 year old chocolate down to the river on nice days for a swim. For some reason she loves to get a mouth full of wet sand and eat it. It is all over here nose and when she comes and licks me, I can actually feel some sand still on her tongue.

Is this something I should worry about, will she grow out of it? I try to get her to stop but all she does it grab a quick mouthful and run off...