Weird. I just pulled my TC reports today and all was fine (with the exception that one CA got deleted!).
Maybe its a fluke and everything will be OK when you pull next...
Or, maybe EX was busy and couldn't provide data to TC. If that's the case, then there were changes to HSBC. If it got re-opened then you could be tagged for a new account (and lowering your avg age, maybe). Heck, I'm writing and probably don't even know.
Did your FAKO scores change any? I know they don't matter, but maybe you can see a trend. Historically for me, but not always, if my FAKOs went down, then FICOs went down, and vice-versa. Did the account totals change? Did you investigate HSBC?