Those wood chips are no good.
I just use liquid pH indicator, it's cheap, it's accurate enough for me, meh, $12 will buy you a lifetime supply.
You can repot at any time if you are very careful. It depends how good your repotting skillz are if you can gently give the lil guys a new home without pissing them off, ya dig?
At this point you should go get some pH indicator and pH up/down like NOW because that looks like the start of a pH issue and you're going to want to do some flushing and most likely adjust the pH of your soil.
Im my opinion and experience, the most common cause of crop failure indoors is crap pH.
You can blame it for I'd say like 75% of the problems I've seen people having.
It's more destructive than nute defs or burns or rot and can manifest as other problem s (lockouts) so the nOOb grower might be like, ph shit, I have to give more food, but really a nice flush/adjustment would have solved everything.