Gurbani by definition detaches one from the world and attaches one to God (which in actuality is no attachment at all). What the mind gets attached to are the concepts in Gurbani. Like virtues, vices, reincarnation, liberation, truthful living, meditation, worship, the concept of almighty, omnipresent, limitless God etc. The mind, constantly attaching itself to objects, can attach itself to these things, and it needs to in order to learn but it must start cultivating detachment in order to progress. It must transcend the system it uses as a crutch.
So yes one can get attached to Gurbani but it is all part of the learning process. If done correctly, no attachment will remain at the end of the process.