That got me thinking about some other recent work I have done. I may like to publish it elsewhere at... And, would this be a threatening subject to talk with him about, now that I am halfway through the contract? Thank you! ~Lisa
Unless otherwise agreed the client owns the work as soon as it is paid for. You can not use it in any way, certainly not publish it, and need the client's permission to even use it or extracts of it, in your portfolio.
(See Upwork's terms of Service)
It is fine and normal to ask permission to post work in your portfolio.
Otherwise, no client wants to hear a freelancer ask if she can use the work the client is paying for somewhere else, because the work doesn't belong to the freelancer.