Is there a non-trivial chance that taking Resveratrol could damage your health?
Well, of course there is, by this community's standards. (Look at the safety concerns raised over melatonin*!)
Is it poison? Probably not. There are sporadic small human studies, and there's general considerations like researchers being drawn to resveratrol because of longevity benefits in populations, which would be inconsistent with it being dangerous.
If I may extrapolate, you are asking 'is the expected utility of resveratrol supplements positive?' The answer is probably yes, but the effect is so small (and resveratrol so expensive) that just about anyth...
From the more-bad-news-for-those-who-want-to-live-forever department: http://pipeline.corante.com/archives/2010/10/08/does_resveratrol_really_work_and_does_srt1720.php
Nor is the bad news just for resveratrol: