Willie, if the fuse blew, the circuit has been overloaded. You don't mention the style of fuse (there are several). I'm speaking about the old glass fuses, now. If the fuse fell apart, or the ends fell off, I would put that down to age. However, the ends don't normally fall off, because they're held by the clips, they usually fall off when you pull them out.
You can get intermittent electrical faults that are a PIA. A little patch of bare wire touching metal occasionally. A wire being occasionally crushed between other parts that move.
It can be a real pain to track down a lot of the time. Look for areas where movement takes place, where things can be hit (taillights are often hit by road debris), or where moisture has crept in.