Hm, I didn't notice such cards. He did play a few cards that gave him a couple of free units, but that just affects the initial units, and one that reduced the movement of one of my unit types.
That certainly aggravated the problem, but it can't be the whole issue.
Of course, if such cards exist and I didn't notice them, it might be the case, yes.
Then I think they should be tweaked a bit, however.