JJ, you are really thinking too hard about this.
If you have another set of tubes, pop those in, along with a new fuse. If it works fine, then you can try switching back to the old set. If it pops, you know you have a bad tube. If not, it was probably something like random like a power surge from the house power.
If it pops on the new set of tubes, take it to a tech. If you don't have another set of tubes, just replace the fuse and see if it pops again.