I have noticed that in the past couple weeks or so Squeaker has been licking metal. She will usually do this after she eats grass or grain.Like usually when I saddle her up,I tie her to the big gas tank beside the house cause it's right by the tack room. I will normally give her a handful of sweet feed either before or after the ride and after she eats it,she will lick the gas tank. If I let her eat beside the road(grass) and then put her in the pen,she will lick on the gate that is metal. She does this all the time now. I am just puzzled as to why she does it. She has a large white salt block in the pen and gets bermuda hay. She usually licks it about 5 times then is done. Is she doing this because she is lacking a mineral? And the metal is not rusty or anything.