That's my guess. You can actually see the fake grout lines, where each tile divides. It makes sense; it's probably safer, less expensive, and more durable to do a faux treatment than use real tiles.
Ah, good eye. I actually didn't notice the grout lines until you mentioned it. I hope they at least apply a bit of plaster or texturing to the surface so that the tiles have that nice rippling, warped effect that the originals do on Leichester. Not that I'm worried. From the brickwork, it's clear they know exactly what they're doing when it comes to realistic aged textures.