Could be a habit, but it could also be that he is needing repetition to process the languge, or it also could be a mild hearing issue, like fluid.
It never hurts to rule out issues when you notice a pattern.
I would ask if you use complicated sentences and maybe he needs more simple structures? There also could be some items in langauge that cause him to need to stop and think, maybe a weekness in a simple process like categorizing (apples, oragnges, bananas-all fruit, but he may need to think for a minute when you say fruit instead of the specific item.)
Since you have enough concern to ask, I would do some primary exploration to rule these things out. Start with your pediatrician.
Developmental issues are too precious to risk missing something that could respond to early intervention.
M.