Not changed but exposure increased

I'm printing with a Beseler 23CIii condenser head. , I start my session for tonight. I do my first test strip and determine the right first exposure. I know I have a good negative at this point already. I make my first print and I have a good initial print just as expected. I need to make my second print to burn up the clouds for just a bit extra. I burn clouds for 1/2 stop Dodging the bottom half of the print. To my surprise it all comes out very overexposed. I didn't change anything !!! Same f stop, same time same grade filter but everything is overexposed. It's like if the bulb just got more powerful all of a sudden...... What gives ? This is very annoying.

Paper problem? Maybe this particular piece of paper was exposed at a time you didn't know about.

Voltage fluctuation?

Inadvertent change to the f/stop?

My enlarging lenses have little levers I can slide to fully open them up for focusing without changing the aperture. If yours does, is it possible you opened it up to double check the focus and forgot to close it back down? Yup, I've done that.

I've done inadvertent f-stop change too... mostly when I open up the lens to check focus, but it's actually 1 stop from wide open. Then when I close it back down it's actually 1 click more stopped down than I think it is. If you did that on your first print + test strips, then the second one would be overexposed.... also double check that your safelight is safe!

P.S. my 105mm lens has illuminated numbers that show the f-stop. I thought that was an un-needed "fancy" feature when I got it, but I've never made that mistake with that lens! Now I appreciate it.