My 12 month old has been waking at 4-4:30 am for quite some time. He usually doesn't require anything to go back to sleep but just wakes crying and grizzly. Sometimes I go in and give him his dummy other times he still has his dummy so I just lay him back down and he goes back to sleep until about 7am. I cannot work out why he is waking at this time and how to get him to just sleep through.
He may be going through a growth spurt and waking hungry, or he may wake, and sensing separation from you, need to be reassured you are there. What you will find with babies, and indeed children as they grow throughout the time they are with you, is that their sleep patterns keep evolving and changing. What is troubling you now, in a few months time will be replaced by something new. I think you are doing exactly the right things! Until he is verbal, you cannot know for sure, so comforting him for a few moments and helping him back to sleep seems exactly right. His waking pattern is certainly not abnormal.