Kenneth G. Wilson (1923). The Columbia Guide to Standard American English. 1993.
after (adv.)
Some purists have argued that after, meaning afterward, should never be used except with a modifying adverb: My ankle got better quickly, but my shoulder pained me long after. (Long after is Standard.) The Irish dialectal I was after going to the store means I had gone to the store or I was about to go to the store.