The exact same thing happened to me (first name and surname switched). I thought it must've been me who enterred it incorrectly, despite the fact that I'm always extra cautious! The fact that it's happened to others definitely suggests a software bug.
I rang up the Manchester office the next day and they told me not to worry about it. I was still worried so rang again to speak to a different agent and got the same response. They said it happens often, so I assume they have seen this a lot of times and are OK with it.