Small Bump Inside Mouth

Hello. I recently noticed/felt a tiny pimple-like bump on the roof of my mouth. I've managed to have a look with a small mirror and it literally looks like a small pimple that's slightly red. It doesn't hurt, doesn't cause me any trouble. No other symptoms of anything, and I have no idea how long its been there. I will obviously go to my dentist but does anyone have any opinions or advice? 

Thanks.