What adhesive did you use on the light strips? The heat generated by the lights eventually destroyed the adhesive on the ones I put up.
Assuming your setup is similar to what's pictured, are you sure it was heat and not that it's stuck to bare wood?
I've got LED strips stuck in an aluminium extrusion which has a clip that is screwed into the timber. I haven't had any issues in the year that I've had mine up.
Sure the Al is a heat sink too, but it is a better substrate for the glue to stick to. Also the end caps also support the wire so there isn't something pulling them down. And it looks a lot neater as well.