Most research universities have IP and commercialization people (our school included), but the purpose of that activity is limited mostly to faculty and grad student projects since those projects often require some non-trivial resources from the university (so they want some ROI). Nearly every undergrad project that a student might claim ownership of doesn't require any school resources beyond the standard stuff (maybe you used lab computers to host your site or code repository for a little while during the semester -- not a big deal).
I think in your situation, since you just want to use it as a portfolio piece, I agree with noahc: just post it, but take it down if asked. If you wanted to use the IP for something that might create significant value (read: you'd make enough to make it worth it for the school or the "customer" to sue), I'd ask first and get something in writing (with the help of lawyer, if possible).
* You're not paid, so it's not their property
* The customer receives all rights to use the software and the source code in order to modify, but they can't sell it (requirement for making it a senior design project), otherwise they'll make $$$ off free labor.
* You are free to use your code/design in portfolios since you created it.
* No NDA's from any party (school, students, or companies)
I would post it. They aren't going to sue you unless you refuse to take it down. If they ask, take it down.
Of course this is contingent on there really being nothing in the contract.