For some reason, when a noun is preceded by the indefinite article “a”, people like to delete the space between them and turn them into adverbs or prepositions, for example. It’s a mistake seen frequently with “a part”, but also with other combinations. The most common example of the space elimination trend is “a lot”, but deleting that space doesn’t actually create a new word.
The same problem doesn’t seem to exist with nouns preceded by the indefinite article “an”.
