I don't think it will be an issue in general. In part because of the type of industry I imagine you are referring is probably similar to government where maturity is valued. In part because 28 is only likely to be an age issue to someone really young or in an organization that chews up young people. Mainly it is because internships are academic and blatant employment discrimination is less likely to occur in that context.
Good luck.
I work at a government lab [0] that regularly has interns that are a bit older than an average undergrad, and vets are preferred. This extends to people the lab employs (a percentage, myself included, are former interns).
[0] https://en.wikipedia.org/wiki/United_States_national_laborat...
If you are willing to try out the Boston area and you like maps or UI/Human Factors, email me so I can introduce you to a contact of mine who commanded medievac helicopters near Basra and is building a startup.