Check Engine light after PCV System Overhaul - 98 Non-Turbo 70 series

[SonicAdventure]

So, I replaced my PCV system this weekend. Repair went according to plan and car started up and ran fine for 40 plus miles, a mixture of highway and city driving.

Had the oil and filter changed this afternoon.

The MIL light went on this evening after a short trip. Put it on the OBD checker and it’s showing a stored P0133 (O2 sensor Circut Slow response) and a pending P0422 (main catalyst efficiency below threshold).

My assumption was that all the shaking around of components under the hood this weekend could have damaged a connection somewhere, not sure. Sounds like maybe my cat is backing up? Is it normal for a car with a fresh PCV to throw some codes after overhaul?

Not sure what the difference between a pending and stored code is either. Anyway, if anyone has any thoughts on this please share. Interestingly, the car is no longer throwing the Evap Leak code that it always used to throw pre-PCV replacement. Thanks.