Yes, perfectly normal. To enable the machine to be ridden on throttle only, there is a freewheel mechanism in the chainwheel. This allows the chainwheel to drive the rear wheel without the pedals turning. When pushed backwards, you will hear the freewheel ratchet pawls clicking. Nothing to worry about.
Really speaking, there should be a chainguard fitted to prevent accidentally sticking your fingers in there when the machine is running on a stand for maintenance purposes. This will be attended to on my own machine during the next few weeks.
Have fun with your new bike.
