the mind 'blanking' on someknown information very briefly, such as spelling of a word, grammatical usage; etc!!
upon looking back, one is left pondering, 'how/why did i do that!!??
-terribly self-embarrassing and a problem not age-specific!!
had some momentary dementia when i spelled your as you're!!, when 'your' was required
momentary dementia made me ignore the concrete fact/s in my head