Yes, you should test pH after an hour or so.

It's important to understand that, with most color based pH tests including phenol red, the low end and high end of the test do NOT mean that the pH is at that level. Instead, it means the pH is at that level OR beyond. A pH reading of 6.8 means "6.8 or lower" and NOT "6.8 exactly".

So . . . your previous box of borax DID do something: it told you that your pH was NOT equal to 6.8, but that it was somewhere below that, possibly MUCH below. If it had been 6.8 exactly, you would have seen an increase.