If the magnets are not quite loose, meaning that with the bunk down off the magnets you should be able to grab them and wobble them around quite a bit. The magnets should not be tight in there mounts. When we looked at our 2015 FR3 30DS I asked if the magnets were to be loose and was told no that they would tighten up. On my drive home the bunk with every bump would fall off the magnets. I've since loosened them up quit a bit and wend out for a test drive and the bunk never once fell off the magnets.
I did however make these supports just in case we have any issues on our up coming trip. If the bunk wants to fall off the magnets I can use these to keep it up, but I feel that now that the magnets are loose I won't need them.
Had this issue on the first run, took it back to the Dealer and they adjusted, no issue since. Can't recall what they did, but they received direction from FR.