Thanks.

corporate-wage-slave has put my mind at ease. I've travelled many times with BA, but I've only booked direct once before. This is the first time I've ever had all letters. I just wanted to make sure there hadn't been some glitch. It's not an actual word, but it has a word like structure (with the positioning of consonants and vowels) so I was worried it was some sort of test PNR which might disappear off the system. But my fears were groundless, so I'm happy now.

Thanks to all for your replies