GRE, authentic signature?

I went to the Thompson-Prometric test centre this afternoon to ensure everything works just fine tomorrow morning (need to be there at but-crack dawn). After having a rather meaningless chat with the receptionist, I shifted the conversation towards identification requirements. My passport is dating back to the middle 90ies, an almost ancient document without any artificial intelligence. Thus, I’m allegedly 1.56m, having blue eyes, specs are an innate part of my face and the signature has absolutely nothing in common with today’s. In fact, I’m now 1.85m (6’1”), my eye colour is green and I haven’t used my glasses for almost five months. Nevertheless, according to the GRE test committee I need to sign in with exactly the same signature as on my bloody 10year old passport, how smart… «go practise it».