LOs have a cycle through the night. The beginning part of it is very deep (the 6-7hr sleep you mention) and the second is rather light (between 3-7am). DH and I found these wakings were for a few different things.
It can be hunger at this age, and even if it's been the regular 3hr from the last feed (1am) it's hard to sleep when your tummy is rumbling.
It can be the dependancy on a prop. The Paci not being in their mouth so they can fall back asleep after waking would wake our ds and we would have to replug. But at this age if your lo is using a paci you should keep it unless it is a prop as los will be able to self soothe without a paci at about 3mo.
Lastly we found that sometimes ds would want to just be awake and coo and we were rushing in. Sometimes he would giggle and wiggle but not really call for us. He would do this for about 45min-1.5hr and then fall back asleep. We found that this was because he wasn't getting enough A time in the day for his age. You might want to look at that.
just a few thoughts on those wakings as we had them too... hth