Indeed we did. All our members brought along a container of tap water, one of tank water, and every pH test kit they could find. These varied from test strips, liquid and electronic over a number of brands. Some were new and some were many years old. All gave the same results no matter how old (or new) they were.
The pH test stuff I use occasionally, when I get curious as I rarely test my water, is about 15 years old and still appears to be accurate. I do not have access to an electronic tester any more but my results are the same as other, newer, tests used.
I have a fancy JBL test lab that Grant won years ago at a conference. The other tests in it are no longer accurate but the pH seems to be fine.