Does anyone know why my new and expensive bath taps dribble after I turn them off??

Have just had some Pegler Visio bath taps fitted which dribble for a couple of seconds after I turn them off. Obviously its not a major problem but they weren't cheap and I'm a bit annoyed that their technical dpt just said its residual water in the spout. I have used taps with much longer spouts that dont do this. Am I being fobbed off? I also have the Visio monobloc basin tap which is due to fitted next week and i'll be well annoyed if it does the same thing. Any thoughts welcome.