This happened to me for a good week or so. I kept seeing faces in patterns everywhere. Floor tiles with texture, bathroom tiles, knots in the wood of benches, tables. It was the most uncomfortable thing ever. My anxiety was really really high, probably the 2nd highest it ever was. I was scared. It wasn't a hallucination. The patterns are really there, we aren't imagining them - our brain just finds these shapes because it's geared to. It's human to find common things (faces, humanoid shapes, etc) in everyday things.
That coupled with an anxious OCD/GAD mind worried about illnesses that encompass hallucinations and such things, make for our brain to "look" for these things. And the more you pay it attention, the more obvious it becomes - just like any obsession. I no longer get any of the "faces in things" symptom. The few times I've gotten it again was because I was up late at night working, staring at my screen a little too long and tired - at that point we might confuse many things for other things, it's totally normal. That's another factor to consider, those who suffer with anxiety will most likely than not be tired - lack of sleep, a mind in overdrive, etc. When you're tired you see things differently. So don't be scared, this kind of thing is normal. You're fine :)