Macbook pro grey screen after ssd installation

I have just replaced the hdd in my macbook pro mid 2009 with a ssd, and used carbon copy cloner to copy my system across. I have booted the macbook on the new ssd and as soon as I press the power button a grey screen comes up with nothing else on it for about 30 seconds before showing the apple logo and then the login screen. After this it's fine and everything is extremely quick compared to before. Is this grey screen a problem as it wasn't there before I replaced the hard drive. I'm on mavericks if that makes a difference