May be thrush. Thrush is a whitish coating inside the mouth (on the tongue, inside the cheeks, the gums, etc...) caused by an overgrowth of yeast (candida). Candida is normally in people's mouths, but in small amounts so is invisible. Thrush is non-urgent if a baby is behaving fine, but should be evaluated by a primary care doctor who can prescribe medication if needed (no over-the-counter treatment available).
No. A white, curdish appearing material inside a baby's mouth would most likely represent a yeast infection or "thrush". It could be as simple as some dried milk curd in the mouth. Try wiping away with a soft cloth or q-tip. Thrush will not be removed. If there has been antibiotic usage, yeast would be more common. In young babies, it can occur for no obvious reason. Medications are available!