Not the slightest bit silly, I do this often with various things I’m looking to buy, that need to be a certain size or fit a certain place.
When I see 1-star reviews on Amazon for people saying “NOT THE SIZE I EXPECTED”, I generally mark them as “not helpful”, muttering about idiots who never look at a ruler (and, frankly, if you give a 1-star review to something because you didn’t look at a ruler, you’re doing a disservice to people looking to find out the quality of the thing actually on sale).