There will be gaps. Spring for a new tube.
I applied some thermal paste from radioshack on my cpu a week ago but then today I was switching the motherboard and I wanted to know cant I just take the heat sink off and just put it back on the new motherboard without reapplying it? I lost my thermal paste and I need to put my cpu in the new motherboard and I wanted to just move it without cleaning and reapplying. Im not switching cpus, Im just moving it.