Hi, I can understand your reasoning, but like you say, she may become realiant on you to help her resettle, this is probably the case, since she wakes at 40 minutes. I would be inclined to step back and see if she can do this for herself, if not go in and do pat/shh. Make sure she is going into the cot before she's asleep, just on the cusp is ok to start with, so that she does the last little bit herself. The same goes for if you ar pat/shh'ing in the cot, just leave a hand on her if you want, then stop all together just before she drifts off. You can gradually decrease your input over a few days or so.
Hope this helps a bit.