I think you are on to something merphd
its all in the way you say it. Neither word is really incorrect
but for me there is a slight difference

burned is still happening or recent event
burnt is past occurrence.

same with these pairs;


burned or burnt
dreamed or dreamt
kneeled or knelt
leaned or leant
leaped or leapt
learned or learnt
smelled or smelt
spelled or spelt
spilled or spilt
spoiled or spoilt