A day after oral sex i got a few red dots on roof of mouth. what could it be?

Oral sex: It likely is caused by bruising from vigorous activity but you could check with your doctor to rule out sdts. You could also have a latex allergy if condoms are used.

Not uncommon : Not uncommon. It's a rupture of small blood vessels from suction. It should resolve in a few days. If not or areas get bigger or painful, it should be check for infection but likely nothing to worry about.

Trauma: Anything viral wouldn't show up the day after, so likely it is slight bruising, or the capillary endings have been bumped and ruptured and it appears as little red dots.