I bought some oleic acid the other day and had it shipped to me. It arrived frozen, and when thawed it turned yellow. Is there something wrong with it?

Check this page out for basic information and a reasonable breakdown on stability of the acid:

http://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma-Aldrich/Product_Information_Sheet/o1008pis.pdf

Otherwise, if you are concerned I suggest calling the guys that sold it to you...should normally be pretty clear liquid...;)

Mark