Was this a glitch in arena?

In arena, aoe & dps, no units spawned for my opponent. I just kept killing each wave until they became to strong and I lost, all the while my opponent only had 1 voltus who he never deployed.

Not the end of the world but, I felt kinda cheated after winning round after round. Each time I killed a wave, it went right to the next round, no guy in the middle attacking his tower because there were no waves alive for him to kill...