I don't think you should worry...if you're comfortable with the way you're doing things now, then there's no need to change. If you feel that it's time to start teaching him to sleep on his own, I suggest very gradually reducing the amount of time you keep your hand on his back. The idea is that he'll be just a little less asleep each time, and he'll get more comfortable with the idea of falling asleep with less help from you.
If he continues to cry after 30 min, you'd have to commit to pat/shh and/or pu/pd at that point to get him through it. Keep us posted!