I noticed my DD1 stuttered a little when she began to say sentences. It was like her brain was moving too fast for her mouth, and she couldn't get out what she wanted to say fast enough. It lasted a couple of months and now it has pretty much stopped. She still very rarely gets stuck but I've noticed it's more when she's thinking of what word she needs to say next if she's unsure. If you are really worried though, like others have said, get it checked out. I'd wait a couple of months just to check that it isn't just a normal developmental thing and if it gets worse or doesn't get better, it's always better to check these things out for peace of mind. Good luck