I would wait until you see him on a sports website and casually ask: "how are they doing?" or a games site and asking "Anything worth buying?" to let him know it's 1-1.
DXC managers know their staff look for jobs (after all, it's DXC, who wouldn't, right?). But the concern would be if you were using work productive time for personal web-browsing. If it were lunchtime, then fine. But given you appear shaken by it, then I am guessing it was productive time.
But who is to say you are not having a late lunch?
I would advise not to approach him. If he's unfriendly, then all you will do is boost his ego of power over you and worse confirm in his own mind you WERE doing something wrong. Whereas there is an element of doubt at the moment.
Just make sure he doesn't catch you again, as that becomes a reportable trend that can be used in his reports, appraisals or whatever "I noticed on at least two occassions..."
I would say, use the evenings to "look around"; ring agencies during lunchtime and then sack your boss by leaving.