I did the same when I was about 12 wks, but I will admit I had not long put it on when I thought to check the tube and then wiped it off again. The chemist recommended just to use the lip balm Carmex (in a little yellow tub - use the tub to prevent cross infection) and suprisingly it worked rather quickly.

Try not to let it worry you, alot of women don't even know they are pregnant at 5weeks and think of all the things they do that can be deemed 'unsafe' before they know they are pregnant and their bubs are fine. Easy to say not to worry though, harder to do, I realise that congrats on your pregnancy