Got a pic? If I'm envisioning it right, then that's just what they do and there is nothing out of the ordinary.

Rodney

A lot of tomato flower petals curl back and then close and shrivel.

Why ? I don't know. That is the way it is.

Sey

I went back out on my balcony and all the flowers look normal now that they are shaded for the last few hours of daylight. I managed to find a picture close to what the flowers looked like. Mine were more curled though even touching the stem in some spots. Here's a better pic http://photos1.blogger.com/blogger/5376/1939/1600/tomatobuds.jpg

Just as with most flowers the age of the bloom controls the petal location. A rose bloom is a good example and the changes are more visible.

They begin closed, gradually open over time as they age until fully expanded, begin to wilt, and then dry up and fall off. It really has no effect on pollination in self-fertile blooms like tomatoes as in many cases they are already pollinated before they even open.

Dave