These events should be unrelated, but I wanted to run this by y'all and see what you thought.

I recently had to pull the radiator on my '89 IROC to get some holes repaired. As I was disconnecting hoses and transmission lines, I decided I'd tape off the transmission lines to avoid getting coolant from the loose radiator hoses in them. Well, as I was reaching down to put the tape on the lower transmission line, I bumped the lower hose and it dripped coolant all over the exposed transmission line. Embarassingly, this happened more than once before I finally managed to get the tape on...

Anyways, I got the radiator back in and have been driving it for the past 2 weeks, and I started noticing that the engine speed would spike for a few seconds between a 3-4 upshift (slippage?). A few days later, I noticed it was having a hard time even getting into 4th. And now, within the past few days, the transmission won't even go into third when it's cold. I was trying to get onto the highway and it was like the transmission dropped into neutral on the 2-3 upshift. I revved the engine some and then thought, no, maybe that'll burn something up, so I coasted for a while. It took about 2 minutes of driving at sub-highway speeds for the gear to finally catch. Now I'm worried that I'm going to loose 2nd gear.

I've checked the transmission fluid and I have at least enough transmission fluid (might even be slightly overfilled, but not by much if at all).

My question: Any idea what the problem might be? Does this sound like water got into the transmission fluid?

Thanks.