If you had a "good amount of yeast on the bottom ot the mason jar" then you had fermentation of your starter. That or a gravity reading are really the only signs of activity for a starter.
Just like in the fermenter, starter fermentation isn't always dynamic...It doesn't matter one blip in your fermenter or your starter flask if the airlock bubbles or not (if you are using an airlock and not tinfoil,) or if you see a krauzen. In fact starter fermentation are some of the fastest or slowest but most importantly, the most boring fermentations out there. Usually it's done withing a few hours of yeast pitch...usually overnight when we are sleeping, and the starter looks like nothing ever happened...except for the little band at the bottom. Or it can take awhile...but
either way there's often no "activity" whatsoever....
I usually run my stirplate for the first 24 hours, then shut it down, if you are spinning your starter it is really hard to get a krausen to form anyway, since it's all spinning, and there's often a head of foam on it from the movement.
All that really matters is that creamy band o yeast at the bottom.
This is a chilled sample so it's flocculated, but even with an unchilled sample you should see a band of yeast at the bottom.
As it is I've only ever seen two krausens actually on my starter, and the evidence of one on the flask at the "waterline" once. But I've never not had a starter take off.
I have NEVER had bad yeast. I have never had a starter not take off or a beer not ferment. And I honestly believe that most people who "think" they have may not have been using the right "signs of fermentation" (like a hydrometer) before pronouncing their yeast D.O.A., never had dead or bad yeast to begin with...they just were using fautly signs.
I think that "bad yeast" is less of an epidemic than most new brewers think there is, and is usually caused by "operator error" (I.e dumping their yeast into boiling or near boiling wort) Or the rare case of yeast damaged in shipment (but I think again, cases of that are overblown and the user using the wrong "signs of fermentation" as well.)
Read this for my take on the idea of bad yeast
https://www.homebrewtalk.com/f163/little-over-48-hours-184027/#post2131342
I'm going to bet that your beer is perfectly fine, and your starter was perfectly fine, especially since you saw yeast in the bottom of the jar.
And again the only "fermentation activity" you need to be concerned with on monday is what your hydrometer says, not anything else, including whether or not your airlock bubbles.
