Yes it's lip tie. My lo has the same problem. Went KKH dental, and they told me it's not an issue. Don't have to purposely correct it. The dentist mentioned they are still young. As they grow the tissue may move upwards and the teeth will eventually close up. If when they are teens already and the gap is still there, then go for braces. Don't have to let them suffer and go for lip tie correction at such young age when they have no problem with eating..
Bring to the dentist if you have any concerned. I believe its better to be safe then sorry. Also just to ensure everything is okay.