No it's not dangerous ...most wood of any desription will have a bacterial bloom as your tank is cycling....This is not harmfull, just unsightly..!!
You can either take the wood out if you can without wrecking the aqauscape and pour boiling water over it and scrub it again, or you can attempt to siphon off the white slime/ mould.
Once your tank is stable and has matured, any clean up crew be it shrimp or fish (oto's) will soon get it cleared if it reappears...