The power steering fluid was just flushed and refilled on my car. The steering seems tighter and requires a little more effort than before. Would changing to new p/s fluid cause this or, as I noticed, having the fluid slightly overfilled cause this?

What kind of problems could occur if the p/s fluid is overfilled? For example, I know overfilling engine oil causes churning and bubbles and eventually lube starvation. What would be the situation in the p/s and pump? Thanks.