No it isn't. -t instead of -ed in general for many words is dialectal for one thing, more commonly retained (a Saxonism) in the West Country than elsewhere. Mis

No it isn't. -t instead of -ed in general for many words is dialectal for one thing, more commonly retained (a Saxonism) in the West Country than elsewhere. Misspelled in particular though is distinctly American, everywhere in Britain uses misspelt. (Ironically, I'm not sure if deliberately ironically, you 'mispelt' both, fwiw.)