Where do you see the AI's recruit levels? The UI at the top of the screen shows your recruits and the remaining population on the left, and your used and total support on the right.
Thousands of units does seem a little excessive, though. If you start a multiplayer skirmish with the AI set to None, you can get the entire starting population of 3500 and build just over a thousand troopers (ignoring support limits, which would drop that to 350 on the default 4 player map if you got all the recruitment sites).
