Peculiar bird behaviour

Hi there :) 

I have bird feeders in my garden and have some great tits that are regular feeders, however there's one bird that seems a bit bolder than the others. 

Most days it will come and sit on the handles of the French doors, hopping from handle to handle, and will either sing, or fly up a few inches and peck on the glass.  It also sits on the window sill of the bedroom and does much the same thing, flies up and taps on the glass.  It woke me up at the crack of dawn this morning, tapping away! 

I'm tempted to leave the doors or window open to see what it will do, I just wondered if this was normal behaviour for a garden bird? 

Thanks in advance for any information :)