It would have to be quite a big frost to affect it. Having a mild frost lasting only a couple of hours in early morning probably won't affect it.
Our weather is too cool for this time of year, mixed in with some teaser days. Our nights are even worse. Hope it warms up soon. We usually do our planting on the 3rd week of May, or the week following, but we are supposed to have frost Monday, so I don't want to plant and then end up covering everything?