Dubious Customer Prolonging Payment (Possible scam?)

[missindulgence]

Hey all, I need your help with a client I've delivered an order for and would like your input and advice.

I have a client who ordered a $125 custom story from me. He's extremely wordy in his request and uses several full messages to try and get his point across. He's also requested four different drafts from me in revisions, each one spaced a couple of days apart.

My gig stipulates that his purchased package only comes with two revisions, but I gave him an extra one because his first (and at the time only requested revision) was a find/replace on some character's names. He keeps wanting to extend the time of the gig with extras, rather than completing the payment. I'm getting a bad vibe and think this might be a scam attempt.

EDIT: After some short insisting, he's finally accepted the order. But I think the worry still stands, and is worth bringing up in case other people working in the Creative Writing fields have experienced similar situations.