Android - Accidentally cancelled update to 2.3 this morning; how do I get it back?

Others are reporting similar issues. Is your build number 4.06, 4.08 or other? I would suspect that if you missed the initial rollout you'll have to wait a bit, since they would want to do it gradually and not overload the network. You might get prompted again later or they might enable manual upgrades at some point.

Verizon says you can update over Wi-Fi, though again it looks to be an automatic thing rather than manual, but maybe you'll get a second notification if you connect to Wi-Fi.

You might try doing a manual update.