No, not at all. I presume one of the explanations for the episodic non-pandemic nature of Ebola is that it mutates frequently.
Just remember, though, that most mutations are harmful to the organism, and that mutations that both increase fitness AND confer increased lethality are very, very rare.
This is like the famously "inevitable" H5N1 mutation that has been "just around the corner" since 1997. Think of it as a slot machine with 18,959 windows (that's the number of base pairs in the EHFV genome). Getting the right combination to confer INCREASED transmissibility while not otherwise harming lethality could occur - just as I could win Powerball Saturday night.
Don't mistake me - I would have closed the West African airports (including Bamako) 3 weeks ago. If we get into trouble quickly, Bamako will be the source. This is easily the worst public health crisis in any of our lifetimes.
But the idea of a random (and not useful) mutation turning the US into Sierra Leone is not on my top 100 concerns about this event.
I don't think viruses make random mutations. They always seem to have a purpose.