Food colouring Sept 09. It is still ok to use isn't it?

[Tortoise]

About to colour icing for DS2's Birthday cake when i realised the blue colour has the date sept 09 on it.
It is ok to use isn't it? (Have some much older colours that i keep for playdoh!)

My mum has a selection of food colourings from the 1970s. I believe she still uses them occasionally!!

I'd have thought it would be ok - it's just a best before date, not a use by.