Domain mapping https redirect issue


I signed up last night to start using your range of plugins which look great, but seem to be struggling with my first implementation. I'm justing domain mapping on a bitnami amazon ami multisite install and although I seem to be able to map domains - i.e. onto whenever I visit in chrome (have only tested it in chrome) I get a privacy error warning as the domain appears to be automatically directing to https. I can only presume I've missed something in the install process. I've got 'force http' selected...

I don't have any ssl certs setup on my sites, but then I'm assuming these are optional rather than necessary for this plugin to work.

Any tips on where I'm going wrong would be great.