If i'm using hand gesture mode and Spark gets stuck and just hovers, could I grab the remote and turn it on and gain control to land?

Yes Its happened to me. just hovers but cant reach it so connect RC and take control to get it down or carry on flying

Great! Thanks for helping with that. I think it got snooty because I was wearing a black shirt

It's more likely you hit the 30m boundary from Palm launch point. When it hits that it just stops and hovers with no way to recover apart from connecting the controller or phone and moving it back inside its perimeter. Eventually it will RTH to launch point if you leave it long enough. Tried and tested.