Is it considered poor form to eat the froth off your coffee with the spoon?

I was having coffee with a friend recently at a local cafe and we both had cappucinos - I did what I always do which was to scooop off three or four spoonsful of froth before I got down to drinking the coffee. My friend looked horrified. I didn't dare ask her why. Did I make a faux pas? I usually only have coffee with my husband, who doesn't drink it himself.