Thanks for the reply. As it turned out, the poly was being sucked into the usealed dry end grain and leaving tiny "beads" on the ends of the wood fibers. I sanded lightly and gave it another coat, and the "frost" disappeared.
After the third coat dried, it was smooth and clear.
I gave it to my DIL on Thanksgiving day and she is still beaming. I scored some major family chick points with it....except that now my other five DIL's want one, and so does my wife and daughter.
Thanks for your thoughtful repy.
Fanaticism is always a sign of repressed doubt...Carl Jung