It is absolutely alright to correct a spelling mistake (irrespective of who made it) in a paper even if it has not been pointed out by the reviewers already. One or two spelling errors are not likely to make a negative impression on the reviewers. However, a grammatically correct and error-free manuscript is always a peer reviewer's delight. Therefore, in the future, please ensure that your paper is free from such errors. It is a good practice to proofread your manuscript well and run it through spell check to make sure there are no such errors.

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